Top thread wont catch bottom thread -i have this machine - is less than a year old - first problem was it would stick if i used it tooo long - now i have a problem with it not catching the bottom thread while stitching material - does fine when metal plate is off but when i put it all back together - no connecting to the bottom thread resulting in no stitch - what am i doing wrong - tried adjusting needle , adjusting bobbin parts - even tried adjusting the catch under the machine - think it is in the timeing but dont know how to fix that - any suggestions?

SOURCE: thread on bottom, bobbin thread loose

Sounds as though you've misthreaded the upper tension. The best way to verify this would be to thread your machine, lower the presser foot on to the material. Now try pulling the thread through the needle. (Assuming your upper tension dial is set to a number greater than one). You should feel resistance. Should you not feel resistance, rethread your upper tension.

SOURCE: skipping stiches

1) It’s possible the machine is threaded incorrectly. Remove the thread completely and rethread the machine. Be sure to use good quality thread--don't buy the cheapest you can find. A good thread will help your machine perform better and your projects last longer.

2) Poor stitch quality can be caused by the needle. Make sure you're using a new needle that's right for the job. Many times machines are taken in for repairs and all they need is a new needle. If you can't remember the last time you changed the needle--it's past time. Needles should be changed at least every eight hours of sewing.

3) When inserting a new needle, make sure the flat side of the needle faces away from the bobbin area. For example, if your machine has a frontloading bobbin, the flat side of the needle faces the back of the machine. If your machine has a side-loading bobbin, the flat side faces the right side of the machine. Some older sergers require special needles that don't have a flat side. Refer to your owner's manual to properly install a serger needle.

4) Thread that shreds or breaks can be blamed on the needle. Use a good thread and make sure the needle eye is large enough for the thread type. Also use the right type of needle for the fabric;
5) The machine tension adjustments put stress on the thread so it doesn't simply flow through the machine. When the upper and lower tensions are balanced, the stitch forms correctly. Tension is easy to adjust--stitch on fabric samples with a different thread colour for the upper and lower threads. Observe the stitch, adjusting the tension until the stitch is formed correctly. As a general rule, adjust the upper tension first. If the stitch still isn't right, adjust the bobbin tension.

SOURCE: Singer CG 550 Top thread keeps wraping around the bobbin and jam

Have you checked the top thread is correctly placed in the spring of the bobbin case?

SOURCE: Jamming brand new machine

the tension on the bobbin case needs to be adjusted to needle size and type of fabric the medium fabrics usually use a size 11, light fabrics need a size 9 and heavy like ( corduroy denim or upholstery fabric needs a 14 or 16 Heavy fabrics need a little less tension on the top side so it will feed properly just play with it until it looks good on a scrap of the same fabric

SOURCE: needle will not sew thread into material

Sounds like the timing is off. Take the bobbin out of the bobbin case and lower the needle into the needle plate. As the needle starts on the upswing, the hook should meet the needle just above the needle eye on most machines. If it isn't meeting at that point then your hook timing will need to be adjusted.