Need Help with 403A Tension Control Please
 

Several months ago, I took apart my 403A's tension knob and now I'm having trouble getting it back together right. I have a schematic to go by and I've taken it apart many times before, so I just don't know what I'm doing wrong. The spring just doesn't have any bounce to it. Any suggestions? Thanks.

~ Cindy

Take it apart and see if it has all the parts.
Did they go in the right order and in the right direction?

As far as I can tell, I have all the parts and I'm putting them in the right order. I'll check again this AM.

~ C

Getting them in the right order and in the right direction can be tough if it was in wrong to begin with - have you considered that the tension might be right but the bobbin area might NOT be right - you can remove the bobbin case and clean the spring - readjust the tension and reinstall. Then there is a spring that holds the bobbin case in that can be adjusted - you never know it could be the culprit. I can not tell you how to do it as well as the repair manual. I just hate it when people twiddle with that.... Now days it is something I check. Before you twiddle with it make darn sure that the bobbin case is in right or you could end up with a good repair bill.
The two circled areas have to be calibrated to work correctly - you can not tell from the photo if this one is correct or not - you will have to use gauges to know for sure:
[ATTACH=CONFIG]510053[/ATTACH]

Make sure the tensions are correctly set. Make sure the bobbin case is properly installed. Then you might want to thread the machine and make a stitch with the plate open so you can watch - does thread hang up as it goes through those two areas I circled? It should pass smoothly through.

In addition - you might check for burrs in the metal any where the thread passes. Dried oil & lint will do the same. Thread can break or just not pass smoothly causing the tension to be off. If you have some burrs you will need to polish them out. I have a machine that still makes tunnels or ditches under the zz stitches. I'm not sure what causes it on that machine. It can be very frustrating. A lot of it is touch, feel and experience. Those OSMGs do have experience. It can take working on a couple hundred machines to know what you are doing - even then there are new things...

I have a 402 that is making loud rattles in that area. Was wondering if it was too loose?? Do you know what the calibrations should be for those areas?

I have never seen a 402 - can you post a picture?
As far as calibrations go - you will need an adjuster's manual

Thanks for everyone's suggestions. I don't think it's the bobbin area, so we can rule that out. The springy wire just won't spring. It's stiff and drops down when the thread puts pressure on it. There is a small groove on the back of the part that has the +and - on it, which looks like it should hold the spring in place, but it doesn't. It might be too worn. Or, I'm just not putting it all back together correctly.

This is my own, personal machine that I've had since 1972. It's not something that I bought off of EBAY. This machine has a LOT of miles on it, but it's still holding up well, other than this problem. It's also my baby, so I really need to get it fixed up right.

~ Cindy

I'll try to take some pix today and post them. ~ C