Thanks Steve and Axelence, it seems the answer is “don’t use electrolytic for 1uf, use film boxes”
And from Steve’s muff’n post, “don’t use a polarized cap unless you are 100% sure the polarity, lest there be ‘fireworks’, but film caps are better”
Researching the MoRC (Ross Compressor) board, C2, C3, and C4 are all 1uf, but C2 and C3 are polarized on the board, whereas C4 is a big box.
So the slightly longer answer is “check the board to determine if 1uf should be electrolytic or a film cap, because it could be both on the same board?”