Repair Radio Grundig RF261U Stereo

Brand: Grundig. Made in Germany 1968. Four bands: FM, AM, SW1, SW2 Solid State: FM 12 circuits, AM 7 circuits AC 115V, 60Hz, 24W max Symptom: AM band worked intermittent. Problem: Band select switches got their contacts oxidized, no good for electrical conductivity. Solve: Disassembled the switches, immersed them in vinegar for an hour then scrubbed with a metal brush to move black stuffs, then placed them back to the board.