Trying to solve a weird problem on Stern Stars 3 drop target bank.

During the bank reset, say the left and center are down. Now the bank resets, the left and center go up but this causes the right most drop to fall. This problem happens inconsistently but often enough to be very noticeable.

Also it could happen with one drop down or two drops down, the raised drops may fall after the bank resets. The lowered drops never fall after reset, only the raised drops fall.

For example suppose X means raised and x means lowered:

Before reset --- after reset
XxX ------------ xXx
XXx ------------ xxX
xXX ------------ Xxx
xxX ------------ XXx
xXx ------------ XxX
Xxx ------------ xXX

I have changed the coil stop and coil sleeve to different ones but it didn't change the problem.

Does anyone think vibration might cause this? Too much slop in the end of travel of the bar that resets the drops?

There's some set screws on there, I haven't yet messed with those.