I noticed that there is no copy on bitsavers of the Konan Corp "The DJ 210" SASI Controller OEM Reference Manual so I posted one on my web site: https://www.vintagecomputer.net/cisc367/Konan_The_DJ_210_SASI.pdf I am not 100% sure, but if I was to guess this info could be applied to repairs for Tandy's and other 5MB hard drives of the era that used the ST506/412 and maybe the Tandon 603S (?) You be the judge, I am not an expert. Bill kennettclassic.com