EM scoring reel or drum-type unit cleaning and maintenance
The most common problem with all of these type mechanisms is that the
switches along the top are dirty or misadjusted causing reset problems.
One of these switches is the zero position switch and will be open
only when the reel is in zero position. Another one of the switches
is the carry switch and will close only when the reel is in 9th
position. This is the switch to check if the reel does not carry properly.
If the problem is match, high score award, or reel combinations (for
slot-type reels) not working--then if the problem is on the score reels it
will be related to the printed circuit board and the associated wiper.
First, check that all the jumpers and connections to the circuit board sides
of the reels are there and good. These have been known to be missing
jumpers from the factory! Check the solder connections to ensure that the
problem is not just a broken wire. By far, most of these types of problems
are wires broken at the solder joint.
If you need to go further, just pop out the spring clip, washer(s), and pull
out the scoring reel. Watch for washers and springs that come out at this
point. Clean the board and contacts with alcohol and then use the normal
minimal coin-lube just before reassembly.
You should also check the EOS (end of stroke) switch--usually located near
the solenoid--ensuring that it has the proper gap and is clean. If this
switch is misadjusted it can cause the reel to appear to be loose and turn
too far, or to not turn enough to step even one digit.