model s all reels sputter during reel test

[puckhead]

i did get to the reels test 1, 40-x . all 3 reels test the same, but i still get reel errors, and they move around , its not consistant.  one reel did test dead, no change what so ever. popping in a reel from my working game got it to pass the 40-x test, but i still get an error on start up. i wonder if the optos are just filthy?

[Stayouttadabunker]

Reel optics don't last forever...they are diodes.
One is an emitter, while the other is a receiver.
Cleaning the dust off of the plastic that covers the reel optics might help....might not.
The optics also have resistors that could be going out of the tolerance windows of their specifications. 

Have you tried the problem reels in the good cabinet yet? If they sputter in that cabinet, then the reels
are at fault.
If they work fine in the good cabinet, then the MPU from the problem machine,  is at fault

Another thing to consider, the reels get their commands from the Reel prom on the MPU.
If the reel prom is losing programming or giving out weird signals, the reel prom could be at fault.
It could be something as simple as an oxidized pin leg getting streaky or flaky electrical connection.
Simple fix sometimes is to remove and re-seat the reel prom back into its' socket making sure no legs get folded underneath the main body of the device.
While you're at unplugging and re-seating, check the power Molex from the power supply connecting onto the motherboard on the floor.
There's a couple of female ground pins that like to oxidize there inside the 6-pin white Molex housing.

However, 9 times out of 10, the problem is with the reel drivers.
Why? Because the reel drivers do a LOT of work trying to hold the reels in place when idle.
AND the reel drivers need their respective IC resistors to be within specs as well.
The reel motors too are under stress...just sitting there holding the reels still in position.

You need to find out which reel motor is causing the 4x errors more often than others.
That reel, from the reel motor and optics down to the reel driver, and to the chip, is suspect.