yes i have a similar problem!
my floppy drive seemed to be working fine until i installed the 3.10e OS upgrade and the MArion Systems SCSI adaptor, i performed the installation myself... as soon as the installation was done the floppy would not read or load any disks at all... it gives me the same error ff60 and says that there is no disk in drive! i was thinking i did something wrong in the installation, maybe i messed something up while doing the upgrade... so i tried to uninstall everything and have it run the old operating system and without the SCSI... the floppy drive still would not read any disk and said there was no disk in the drive again! it also gave me an error number ff40 this time... so i reinstalled the upgrades again and it still would not read floppies... so now i have an mpc60II with 3.10e OS and SCSI, but the floppy drive wont work!

i called Roger Linn Design, and the guy i talked to there told me to try wiggling the wires connected to the floppy around, and suggested maybe i did accidentally mess up some of the connectors/wires inside... i tried this to no avail, and he also recommended that i call either VST or FORAT, i cant remember which place it was at the moment! but anyway, i called them and told them my problem... the very first thing the guy told me after hearing that the floppy worked until i installed the OS upgrade and didnt work at all after that was:
"you have a floppy drive that was probably ordered from
ROUTE 66 and that floppies from them do not work with the 3.10e OS!!! since i bought this piece used and dont know if it is indeed a
ROUTE 66 floppy drive... im wondering if there is anyone else out there that is having this same problem? or does anyone out there have an mpc60 with OS3.10e installed and also have a floppy drive from
ROUTE 66??? id like to find out before i shell out $135 bucks to have a new floppy installed... also, anyone know where to get a better deal on a floppy drive????
help please...