<Remember, all older MFM, ESDI and some early SCSI drives always need <annual or bi yearly LLF job. I have a st506 that I formatted once and never again and it still works fine. I do however run a program that checks it for bad sectors, haven't found many over the years. The need for reformats is urban legend and I have a bunch of RD52/53/54(mfm) and a potload of st506 and st412 drives that haven't been reformatted unless moved to a different system where the controller was incompatable with the former format. However to qualify that I've seen many systems with power down problems where they would write garbage to the disk causeing a need for reformats. I've also seen system with power and heat problems. Optimally the drive should run over a narrow temperature range that is centered at the temperature they were formatted at. most time they are asked to run much hotter and that means the stepper is not centered on the thermally repostioned tracks. This can be made worse by reformatting the drive as cold as it will warm up and all the track centering will be off leading to errors and a likely reformat. Later voicecoil and other servo positioned drives are immune to this as the servo track or embedded servo information will insure it tracks with temperature and bearing wear. Allison