Fanuc 3m help

I just bought a Yuasa CNC mill off of ebay, and I need a little help
getting it going. It is a 1981 model and has a Fanuc 3M control. I
keep getting an error that means the Z encoder cable is disconnected,
and following the troubleshooting guide in the manual (swapping cables
and such) I've concluded the mainboard is bad. Does anybody know where
I can get this repaired at a reasonable price (less than $1000)? Fanuc
says it has a flat rate for repair on this board, I'm not sure how they
do that, but was $2260. WOW! Anyway, I'd really like to get this thing
going.
Thanks
Nathan Clymer