Two things that continued to be unpredictable on the 8810 were the top thread fouling and the presser foot loosing pressure.
Maybe these things never happen on your machine but on mine it happened just enough to get my attention.
The top thread would on rare occasion jump over and around the tension adjustment knob, strangely enough it might stitch for a while that way too.
It is hard to see and when it happens it is frustrating.
The fix is really simple and speaks to the design flaw as I see it.
Its easier to thread and the thread loop never gets near any of the other parts, problem solved.
The next issue was the gear driven pressure foot that would always hang up if I lifted my foot off the pedal too slowly.
When you look at the entire system from the pedal to the gear driven foot there are about a dozen places for friction to accumulate. I felt that the real "sticking" point was at the last sliding shaft.
My solution was to add a small compresion spring around that shaft and no more more hanging up!