Tek T900-series
The six models of the Tektronix T900-series (T912, T921, T922, T922R, T932, T935) are all pretty easy to work on. The T922R is just a T922 with the guts rearranged into a standard 19" rack-mountable package. Oilfield wireline services probable bought more T922Rs than any other segment of electronics and they loved them. By racking the circuits in the T922R, the biggest problem of the T921, T921 and T922 is eliminated: cold-soldered power supply connectors. The female P/S connectors in the non-racked scopes had a nasty habit of working loose from the PCB. I always resoldered these whenever one of those models came in for service.
The T922 and T922R use the same service manual. It's a dual-channel, single-timebase, 15MHz bandwidth scope with automatic TV sync available in the trigger circuit. A lot of folks didn't like Tek's T900-series scopes, but they were comparing them to their usual high-end stuff, which was hardly fair. The T900s were developed as a low-end scope to replace the Telequipment scope line made in the U.K. which was a burden on the Tek profit margin.
Dean