Wanted: WD1002-HDD docs or Teac SD-520U help

I recently received a PCjr add-on which is so unusual, it felt like Christmas. But as always, it needs a little TLC. This is an expansion chassis made by an outfit called "Legacy Technology" in Nebraska in the mid to late 80s. The interesting part of the chassis is a hard drive controller card and hard drive. PCjrs only had hard drives if you bought a 3rd party controller, and they were all pretty hackish. The drive is a 20MB Teac SD-520U and it is very flakey - I am getting data corruption almost all of the time. The corruption seems random; this drive might just be tired. I've low level formatted the drive twice. The controller BIOS supports INT 13, Function 7 (Low Level Format). It's not helping. Since the drive is probably not usable, I'm trying to figure out how to substitute in another drive. Examination of the BIOS extension shows that the controller supports 3 types of 20MB drives and 1 type of 10MB drive. I have 10MB drives that I can use, but not another 20MB drive. This is an XT class controller so I'm expecting to find some jumpers to set the drive type, but they are eluding me. The controller is actually a two part affair - A small amount of logic with the system BIOS extension on it, and then a WD1002-HDD board. The WD1002-HDD board mounts to the underside of the hard drive and then connects to the hard drive using the familiar 34+20 wire ribbon cables. It looks like it is capable of controlling three separate drives; it only has one 34 pin connector, but it has three 20 pin headers, one of which is in use. Does anybody have docs for the WD1002-HDD? If so, where do I find the drive type jumpers on the board? If I can't figure the controllers out I'm going to be looking for a similar drive. I suspect the trusty ST-225 works - the geometry is the same. Regards, Mike