How do you do a correct timing adjustment on the white sl34 serger

SOURCE: needles break and machine jams

TIPS FOR SUCCESSFUL SERGING WITH WHITE SERGERS
http://www.whitesewing.com/PDFs/Serger_Tips.pdf

SOURCE: Thread tension?

I own this little gem of a machine. It definitely sews a perfect stitch. I'm assuming you own the green 3/4 size machine as denoted by your product number. The half size blue one pictured is incorrect.

Anyway, this machine sews a perfect stitch, due to the oscillating bobbin. Most sewing machines with rotary (drop in) bobbins don't have an easily accessible bobbin tension screw, which means your fabric is usually slightly puckered. Fiddling with only the upper tension helps very little. This frustrates me to no end for sewing long curtains, clothing side seams, etc. Wrong tension causes them to hang with puckers, making them look awful. With the Hello Kitty 3/4 size Janome, there is a screw on the bobbin case which allows you to adjust for every thread diameter perfectly. Always a perfect stitch, if you take the time to adjust this screw.

To adjust the bobbin for a perfect tension, load the bobbin into the bobbin case and thread it through the guide. Holding only the thread between two or three fingers, let the bobbin case dangle below. This will be slightly difficult, because the bobbin will want to fall out of the case. Don't worry, just don't move it around too much and it will stay in long enough for this test. If the metal bobbin case slowly drops lower, unwinding thread as it goes, the thread is too loose. Tighten the screw on the side of the bobbin case a little (about a quarter turn.)

If the bobbin case seems to be dangling firmly, give the thread a gentle tug, lifting up fairly quickly. If it doesn't release a couple of inches of thread, it's too tight, loosen the screw. You know the tension is perfect when a quick, light tug of the thread releases a couple of inches of thread.

SOURCE: consew 226 r sewing machine

Take the bobbin out and check for dirt or broken thread in the hole.

SOURCE: CLICK AND GRIND IN 270D BROTHER SEWNG MACHINE

This happened to me and I discovered that my presser foot was stuck up. (LOL) I was using embroidery and the needle was actually brushing against the raised presser foot. So, I turned machine off, removed embroidery part and checked the presser foot switch. It was not moving. Well, I put the machine on regular sewing and just turned the wheel a few times and the presser foot reset. When I went back to embroidery all was fine (and still is). so, check yours.

SOURCE: I have a baby lock ea-605 serger

Assuming that (a) you have tried installing new needles, (b) the new needles are the correct system for the serger and the right size (typically size 14 for medium-weight fabrics, size 11 for lighter-weight fabrics), (c) the needles are installed correctly (inserted all the way up into the needle bar and facing the proper direction), then your machine is likely out of time and / or has a defective part such as an upper / lower looper. That will require professional attention to correct.