Have you gone through it and clean/lubed the step units? tightened switch stacks?
There are other switches along the line to satisfy the reset.
The ball count unit, player unit, credit unit, i think all have switches that need to be workin correctly.
and chk the coin switches also

I would call Steve at pbresource.com and see about getting a schematic. I understand he's the go-to EM guy. It's going to be tough to fix without one.

Hi sandslinger
I believe: on One or on Two, 3, 4 ... Score-Reel(s) the "Zero-Break-Switch" is / are faulty closed. If JUST ONE of them IS FAULTY-CLOSED: The Reset will not / never stop.

There are 16 (!) score-Reels to check - want to do a little test to prove me "right" or to prove me "wrong" ?

Unplug the 110 VAC Line Cord (safety reason). Look at my JPG -> the drawing of the relay -> Switch "A". Look in your pin -> the Reset-Relay -> sneak-in a stripe of paper INTO this switch - the stripe pf paper is for INSULATION - I want THIS SWITCH OPEN.
Take a screwdriver and hold its tip at the two blades of this switch -> take the screwdriver away -> put it back on there -> take it away. Practice this a bit ...
when you put the tip of the screwdriver there - touching both blades: You make a "Micro-Jumpering".

Have the paperstripe IN THAT SWITCH - Plug-in the Line Cord. YOU hold the Screwdriver at the switch - a friend pushes the Replay-Button -> the pin starts the reset - > after the Score-Reels are resetted -> YOU TAKE AWAY THE SCREWDRIVER
AAA) The Reset-Relay stops pulling -> You have proven me "right".
BBB) The Reset-Relay keps-on pulling -> You have proven me "wrong".

The stripe of paper in the switch simulates "ALL 16 Drum Unit Zero Break Switches ARE OPEN"
Please do this test, depending on Your answer: We will look "here" or we will look "there" ...

(((Want to look into the manual of Cabaret. http://www.ipdb.org/machine.cgi?id=415 -> page-15 -> each Score-Reel has an arm / finger - it moves THREE switches. One switch is the "Pos-9-switch, it is not of interest". The "Top" switch and the "Middle" switch are for the Reset-Cycle: 16 Score-Reels times TWO (switches per Reel) ? 32 Switches to check - I think "my little test" is worth trying / saving time (if You prove me "wrong") ...
Greetings Rolf

aPat-Hand-Reset-Relay_(resized).jpg

Hi sandslinger
want to read the little story about 16 men sitting in a room ... -> https://pinside.com/pinball/forum/topic/help-with-williams-dealers-choice#post-2541079
AND BEFORE LOOKING AT ALL 16 Score-Reels: Do the test "in here, post-4". Greetings Rolf