Marty:Floppy Drive Repair
FDD Repair
Marty uses a brittle and trash FDD called Matsushita EME-215 or EME-216. It is also used coincidentally by more expensive MSX computers such as MSX-A1GT. It is a 26 pin FFC bezel-less drive.
Marty FDD with melted belt
Clean the Belt residue off the motor and everywhere else first
Over time the drive belt has melted and needs to be replaced. When replacing the drive belt note to remove the remnants of the old belt from the pulleys on the drive.
It's also recommended to clean the 26 Pin FFC Connector on both sides.
However, one issue plaguing this drive is the drive IC is commonly burned out. Even after cleaning the floppy drive heads along with changing the belt, it will only read and not have write capability.
Belt replacement
Console5 has a belt replacement available for the FM Towns Marty FDD.
FDD Replacement
So you decided to replace the garbage drive with a more reliable drive. Luckily some PC drives can be modified to work in Japanese Retro Computers and this includes Marty.
First, you need a 3-Mode bezel-less floppy drive. Commonly the SFD-312B can be modified for 3-Mode operation. I cannot provide photos as there are so many versions and variants of it. Following the service manual for that specific floppy drive, however, can net you positive results.
The modification includes removing the 26P FFC connector from the dead drive and cutting up a 34P standard floppy cable to connect all the signals together. A PCB would be cleaner looking though.