Did you get a new motor or a used motor? Wipers on a dry windshield will
often drag and operate slow, but they shouldn't on a wet windshield. Don't
bother with the fuse - it's either good or it's not and if it's not, the
wipers won't work at all.
Have you checked the bearings where the wiper arms attach. If either or
both is dry (not uncommon), they will slow down the wiper action. Work
some oil into them (real oil, not WD-40 or another light spray lube) and
you should see a big improvement.
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