Daniel, post pics of the blanked off height control system. We are both curious. The height control solenoid and the Lo & Hi restrictors are not involved with the M/C. The MC is totally separate.
My prediction is: The M/C is not returning to rest due to a problem with the unit itself, or thereafter, ie. rods, bushings, springs.
Let us know the results of physically disconnecting the M/C from the trap. It may speak volumes and like we said earlier, isolate things.
Problem solving involves throwing everything on the board, exploring possibilities, and crossing them off going forward.
The M/C circuit, in terms of the big hydraulic picture, is simple and straight forward.
You may want to PM Jim Walters who contributes regularly. He is in BC and has decades of experience. Suggest to him to have look at the thread and perhaps he can assist.
1980 SWII LRL-41587C FInj
1976 SS LWB LRE-23114 Harkness RR