Ok, so I had my lower rad hose heater plugged in for a few hours this morning because I had a doctor's appointment this morning and wanted to make sure the car started. Unplugged the heater, went to start the car, thought it sounded "funny," so I turned it off and restarted it. Suddenly the engine would barely crank, like the battery just suddenly died. I put my battery on a charger and consulted my husband via IM, who said to tighten the screw on the positive battery terminal. I did so, and then the car started, though it did run unusually noisy for a minute or so, then quieted down to its normal level.

May or may not be related: last week my starter got stuck, but luckily the husband was with me and he undid the terminal, gave something (the solenoid?) a few whacks with a wrench, reconnected the terminal, and the starter problem was gone.

Are these related? Do I need to replace the solenoid, or is this just the result of me killing the battery doing cold starts a lot before I got the hose heater?

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1983 240D, 272K+ miles (odo broke)