I recently painted a spare set of alloy wheels. Unfortunately, the lighting in my unit is not good.
After the paint dried, I noticed a couple of spokes hadn't been fully covered so the primer is showing through.
You should be able to throw another coat of paint on top of the existing coat to cover the missed spots. Be sure to let the paint dry before putting another coat on, and if it looks uneven, throw another coat on. After a couple coats the wet paint should fill any holes you missed on the previous coats.