HELP! Compressor now trips breaker on start up??

The capacitor should have the rating in microfarads stamped on it. Usually expressed as 10mf or 12.5uf. Some of them (usually black plastic case) have a range like 125-180 mf on them. You'll just need a meter that reads microfarads to test. There are switches rated for higher amps . They look like a breaker without a value on them. They fit in an enclosure like a disconnect or single breaker housing. Whatever you do, don't exceed the capacity of the wire with a breaker that is rated too high. 12 ga wire needs a 20 amp or lower breaker.