Flasher-Turn Signal Relay diagnosis: 1985 300D

[dogguy]

About a year ago, I noticed that when I used my turn signals, they were operating incorrectly:
Left/right dashboard indicator flashing rapidly.
Or sometimes...
Left/right dashboard indicator not flashing and instead staying constantly illuminated.

I checked each turn signal bulb in the front and rear and confirmed all were operating correctly. Even swapped with new bulbs, tried the turn signals, and the incorrect operation continued.

I have removed and opened the flasher-turn signal relay (pic 1 and pic 2) and tested it. Pic 3 shows me using a grounded test light on pin 49a and the notation shows what happens (very rapid vibration and audible buzzing). My guess (perhaps someone who knows can confirm or repudiate this):
The relay is not supposed to rapidly vibrate and buzz loudly. Stated another way: The copper plate that moves/vibrates should be a slower and more syncopated click-click-click-click as one would expect for a turn signal relay. Yes or no?

Given the current operation of the relay, perhaps it has failed? It is stamped "4/85" on the outside so it has seen a lot of years of work.

I'd appreciate any insight on this little situation. Thanks-