the 922-K and 922-L schematics are on
http://bingo.cdyn.com/slots/ ... the w-1046-xxx files are the schematics in the subdirectories/folders.
per the schem, the lock should have a switch with yellow (30) and green/red (41-4) wires on it. Every time you twist the key to close then open the switch, the jackpot reels for the jackpot currently selected by the jackpot total step up disc should all increment one number unless they are at zero.
so resetting a jackpot means you have to twist the key up to 9 times to get all the reels to zero. In practice, it may be simpler to just manually step the jackpot reels and start them at whatever number you want.
when the key switch is closed and one of the jackpot reset relays is powered, the coin lockout coil is powered and you can drop a coin in to release the handle and reset the line unit when a 5th coin played jackpot is won. It's easier to just manually trigger the coin switch and it doesn't matter what the key switch is doing.
the idea was some casinos didn't give the floor people access to inside the machine, so they needed a way for those folks to release the jackpot lockup after hand-paying the balance of the win that the machine didn't pay. The person would turn the key and drop in a coin to get the game out of lockup, and usually the casino person would pull the handle. If that resulted in a win, the player got to keep it :-)
in this case, the person would turn the key and reset the jackpot reels for the whichever jackpot (upper or lower) was won.
I'm not sure what the actual lock/switch looks like on that machine. If you can email highest possible resolution pictures of the lock to slotpics@cdyn.com ... and the entire machine front as well as any internal pictures you'd care to take - especially both sides of the to insert board with the jackpot reels - I'll add them to the web site. If sending from a phone, send "actual size" and take pic of the entire area rather than many close-ups.