[Coco] Disk controllers

[Bill]

I have two "spare" disk controllers that are not working properly, and I
don't know if it's the controllers themselves or one (or all of) the chips
inside.

One is a 26-3022, and the other is a 26-3029. 

The 26-3029 has a chip inside labeled:

 SCM92128P 
  8045364A
TANDY 1982
     8455

When the cable is plugged in (not even inserted in the Coco), immediately
both drive lights come on. When I swap out DECB chips, only the DRIVE 0
light comes on. Needless to say, there is no using it.

The 26-3022 chip is labeled:

SCM92128P
  8045364A
TANDY 1982
     8622

When the either chip is inserted into a 26-3129 controller they will not
work. No DIR, no DOS no DSKINI command.

The chip in the 26-3129 controller (a known-working controller) is labeled:

TMS4764-30NL
B8428L
ZA64342
804-5364A
1982 TANDY
SINGAPORE

And when inserted into the 26-3022 controller, it will do nothing.
Regardless of which chip is put into the 26-3029 controller, it still acts
the same.

Ideas?

Thanks