What makes you think you have a bad CMOS ram? usually you just need to do a Ram Clear. You'll need the Clear chip to clear the error. If you have a bill acceptor, you'll need a Set chip, too. usually you can get a set for about $25...
Error 61 means you have a memory failure - usually because the battery went bad. replace the battery, then see if you can clear the error by turning your jackpot key to advance thru the different tests, then shut your door. If you still have an error, then you need to do a SafeRAM Clear. You will insert the Clear chip where the game ROM is now, turn it on, let it boot up, cycle thru again (I think) then turn it off and put the game ROM back in. If you have a bill acceptor, you will need to get a Set chip also, and do the same thing.
It's fairly easy to accomplish. Several of the guys over at www.newlifegames.net sell the Clear and Set chips fairly cheaply....