Bernina 830
I guess this wonderful machine falls into vintage category. I got it as a hand-me-down years ago and I have used it occasionally. Never had many problems but now working on a cushion cover project I have had lots of problems with top thread bunching up under the fabric. After lots of looking at YouTube etc I have pretty much concluded and proved the issue was the top tensioning.
Here is my question. When I was getting going, I checked to see how to thread through the tensioner on top. The disc on my machine was more or less in the middle of the slot so I did not know on which side the thread went. Tried either side, lots of tension adjustment.....lots of great sewing interrupted by frequent big bunchups. As I mentioned, after lots of frustration I concluded the tensioner was not right. The thread seemed to keep popping out towards the top of the slot and getting loose.
So, I took the tensioner out of the top cover and found some (not lots) fuzz etc in there. After cleaning it up with alcohol, the disc now seems to go to the right side when not engaged, not really allowing the thread to to go on either side. It has to go on the left side and now the machine seems to work fine,,,,,no issues. I also but a tiny drop of oil on the push rod that disengages the tension disc. That pin was sticky
I think I solved the problem and I have no regrets since this is a a nice machine and given its age, a clean up was in order. Am I on the right track? Did my fix really attack the tensioning problem? Seems to me it did but I am wondering if there is anything else to look at. Thanks for others experience