The MC-2100 (looks like a MC-240 tube amp) and the MC-2105 (black glass, gold lettering, blue meters) are workhorses that still sound good!
You might find 2100's for $500, 2105's for $700. Still supported in Binghamton, Motorola output TR's in stock @ $10 ea. Try one - you'll like it!
I sold dozens of these in the mid '70's for home HiFi and nightclub music systems, a few to local bands for PA, never had a single failure!
Front: Stacked Klipsch KG4's on top of Forte' II's, Titanium HF's. All in parallel: 2.7 ohm load.
Power: Adcom GFA-555, dbx 3BX II, mild +/- 3 dB room EQ
6 powered subs: Klipsch Sub-12 and Bag End InfraSub 18, dbx 120X sub-harmonic synthesizer
Center: 2 KG2's, Rear: stacked KG4.2's + SS1's
Test Gear: Behringer DEQ-2496 + ECM-8000 RTA & SPL meter