According to the excellent wire diagrams that PapaJam provides, fuse #5 (counting L>R) controls the key buzzer, int. wipers, turn signals, fusebox light & radio. Sounds like you should start by cleaning the fuse contacts and replace that fuse. Even if it
looks OK - replace it anyway.
It might also be a good idea to lower the fuse box and peek at the back. Look for any loose connections. Especially behind the location of the #5 fuse. (Here's how to
drop the fuse box.)
Below is a look at the back of the fuse box in our '84 Spider. Note that the yellow plastic block in the bottom row is a little crooked. Among others, it was loose...