Singer5050 sews a little then jams top thread in pieces in bobbin area

adjust the tension to a appropriate setting,
See the video here.
Sewing Help Sewing Machine Problem Thread Bunching Under Fabric
The knob and its location can differ based on the model of your sewing machine.

Remove all remnants of the thread from the bobbin area.
First thing first - thread inside bobbin should be tightly wound in. Insert bobbin into bobbin case and thread through slot and under the spring. Spring has small screw which regulates the tension. Hold the lot by thread like yo-yo and jerk a little down-up. It should drop just a little (not run down) - that is usually required bottom thread tension,
if not, regulate with the screw. Set top thread tension 3 and sew. If still looping under, increase the top tension higher till the looping disappears. Also try new needle.

Maureen--Here are some things to try to make your sewing experience more pleasant:

First thing: Put in a brand-new needle. Damaged needles are probably the number one cause of a sewing machine issue. For some reason, sewists are very frugal with their needle supply. However, needles should be replaced frequently to achieve the best sewing result and the least problem. Needles are a very inexpensive "fix" for frustrating issues. Also, do NOT sew over pins. It will not only damage the needle and possibly knock the machine out of time but is also dangerous because broken needle pieces can fly a long distance--into your eye or elsewhere.

Try a different type thread. Old and inexpensive brands of thread can cause problems.

Clean any dust, lint, and thread pieces from the feed dogs and bobbin area. Be sure to oil your machine as recommended in your owner's manual. Use ONLY good quality sewing machine oil (not 3-in-1, grandma's old oil tin, WD-40, or cooking oil), and apply only one to two drops each spot as directed in your manual.

Clean the tension disks. Remove all the thread from the machine. Loosen the upper thread tension as much as possible, then gently pull a piece of UN-waxed dental floss or pearl cotton between the tension disks to clean them and remove any dust, lint, gunk, or pieces of thread. Do this several times to get everything removed that shouldn't belong.

Be sure to RAISE the presser foot BEFORE threading the upper thread (this releases the tension disks so the thread will seat properly).

Re-thread from the beginning verifying that it is threaded properly (consult your manual).

If your thread is globbing up under the fabric, you are probably experiencing thread nesting or birds nesting. Here's a handy web site:
Sewing Machine Thread Bunching Up Here Why

sewing machine birdnesting

Usually birdnesting occurs when the upper tension is too loose. Try tightening and then test.

If the upper thread is pulling the bobbin thread to the top of the fabric or is breaking while stitching, the tension is too tight. Try loosening and test.

The tension is correct when both, the upper thread and bobbin thread, meet in the middle of the fabric.

As a sewist, you will be using different weights of thread and fabric as well as different sizes and types of needles, so adjusting the upper tension to suit each circumstance should become second nature for you. This web site may be helpful when determining which needles to use for which project: All About Needles

Adjusting bobbin tension should be attempted only if you understand the consequences. Bobbin tension should be done only in small increments and you should be able to comfortably return it to the original setting.
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HANDY TIP: to help threading the needle's eye, instead of licking the end of the thread, lick your finger and then swipe it across the back side of the needle's eye. The moisture in the eye will draw the thread into place.

if you are getting loops on the underside of the fabric or jamming around the bobbin, then your top thread is not under tension or going through the thread take up lever, that little arm that moves up and down. Recheck your threading path making sure you always raise the presser foot to open up the tension discs so that the thread lies into the tension discs fully. Also check that you have the bobbin threaded up correctly into the bobbin case, with the thread caught into the tension spring (you will hear a little click as it goes in). The bobbin will turn anticlockwise as you draw thread out of it. Use the top thread to raise the bottom thread up, replace the needle plate and bobbin case cover in place, then take both threads to the back of the sewing area. Hold them firmly as you start sewing! very important that you don't allow the thread tails to be caught and dragged into the bobbin as they will jam around the rotary hook.

The white bobbin thread was showing on the top of the material correct? Make sure bobbin thread is in the tension correctly, check the top thread spool and make sure thread is not caught around it, if you have a manual top tension make sure that is set correctly. Personally I would never use wd40 in a sewing machine, sewing machine specific oil is always better. You seem to be describing two different problems. The thread bunching is probably from the thread jump out of the take up lever.

try rethread the machine top & bobbin
change the needle
clean under the needle plate & in the bobbin area for lint & loose
threads

Thread jams underneath usually are caused by top thread tension issues. Things to check:
top tension discs are clean and no thread traces caught in there, tension is set to medium number usually 4 or 5 and that the top thread is running freely from the thread spool, correctly thread through the tension discs, and down to the needle. Lower the pressure foot and pull the thread from just above the needle; it should feel firm resistance if under tension correctly.

As you've had a good jam up, good idea to now remove the bobbin, needle plate and bobbin holder (refer to your manual if you have never done this before) and clean out the hook area well, look for any fine thread remants and brush out any lint etc. Oil the rotary hook area as per your manual. Now reassemble, and rethread everything again checking that the bobbin thread is clicked into the tension spring and that the top thread is through the tension discs correctly.

Also, pop in a new needle, flat shank to the back, then try again.

Good luck with your machine.

No top tension, follow manual to thread top again and make sure tension dial is set to 5 and thread is pulled between the tension discs fully.

Tighten the bobbin thread a little and loosen the top thread tension a little. A correctly tensioned embroidery machine will show a little less than 1/3 of the top thread color and 2/3 of the bobbin thread on the bottom side of the embroidered piece. You may have to play with it some so use scrap material and dark top thread until you get your adjustment made.

If it was sewing correctly BEFORE the needle break...why did the needle break in the first place?...and what fixes did you make?
If it sewed properly...what changed?

Cut your upper thread close to the spool...make sure the presser foot is raised and pull the cut off thread section through/out of the machine from the needle area (sewing direction...do not pull the thread backwards!)

Clean out the bobbin area...remove any traces of lint or pieces of thread...look for any broken off needle pieces... brush the bobbin area out....then add a drop of sewing machine oil (but only if your manual says to oil that area).

Remove the needle plate to expose the feed dogs...brush/clean out that area too and add a drop of sewing machine oil...then secure the needle plate back on.
Replace the needle...do it again...yup...some needles arrive bad from the factory. Make sure the needle is inserted and positioned properly. Then thread the machine WITH the presser foot in raised position. (The thread needs to get seated into the upper tensions.)
..with the.presser foot down...thread the new needle.
Oh...and use the correct needle for the thread. (a universal 80/12 is standard).
Thread can cause issues too. Try a different bobbin, or maybe a different spool of thread to see if that makes a difference.