1985 300SD
Problem with turn signals. No electrical work done since battery change last yr until this wk.

For 2 months, turn signals sometimes normal. Sometimes flash intermittently. Sometimes do not come on. Sometimes buzz like a bee instead of just blinking. When signals buzz, the turn signal light on IP flickers as fast as buzzing.

1 week, turn signals would mostly not come on at all. Sometimes turning the hazard flasher on and off dozens of times would return turn signals to normal. Sometimes not. Looked at turn signal exterior bulbs, all 4 turn on [after jumpering 30 to 49a as below].

Cleaned the hazard flasher according to the peach parts wiki.

Turn signals worse. Worked normally one time then totally off. Hazard flasher worked once now not working at all.

Saw post about jumping connector to hazard flasher. Jumping 30 to 49 did nothing that I could see.
Jumped 30 to 49a and turn signals would come on and not blink if signal lever pushed to left or right turn signal position. Now drive car with signalling by moving turn signal lever on and off.

Replaced fuse #12 with a spare and sandpapered the fuse ends and terminals for #12 on the fuse compartment. No change. Radio always works normally whenever turned on; radio is fuse #12. Not aware if any other fuse is involved in turn signals or hazard flasher.

What other tests to tell if hazard flasher, relay or turn signal combo switch or something else is defective. Thanks.