Up for sale/trade I've got a 4m Bung/Makko Famicom Game Doctor along with a copy of the Copy Master software on an FDS disk. With the combination of these two items you can do a number of things. For FDS fanatics, you can tune your FDS motor to the proper speed to all but eliminate those evil disk errors. You can also copy FDS disks and with the FDS Loader cable (not included) you can re-write those disks which have lost their data over the years.
Copy Master software:
I'm a bit new around here, but have over 100 positive EBay feedbacks.