magnets and reed's, check them might be getting week or got moved. did you check you lock's are you hitting a roller?

How many stops? Does it happen every time? Only at the bottom floor?

How is the adjustment on the valve..maxton uc4m..check the down leveling as well as the down stop settings...leveling inductor good.might want to look at the down slowdown roller on the limit switch as well,if all is good try moving the magnet up a bit and see if anything changes..

What happens after it stops? If the DMV and dlv relays in the controller are dropping out, then the processor is shutting off the run sequence. In this case look for DR input going off, or BT input changing state before seeing the level down or door zone input. If the down relays are staying energized in the controller check the L3s or l9s limit switches. Check to see that 1pi input changed as it was coming down. I believe the sequence would be 1pi, to step to 1st floor, drop hi speed relay DMV , look for ld input to go on and drop dlv relay when ld input goes off. BT input is bottom reset switch.