Looking for some help on with AC electrical issue.

Over the weekend we returned from a cruise and plugged into shore power. Shortly thereafter, smelled electrical burning. Shut things down and took ac panel cover off and found line wires burned at connection to the circuit breaker that is connected to AC unit 2. The wire that burned is the one providing power from shore #2 main breaker (shore #2 has 2 ac units and ac water pump), as best I can tell. The other two circuit breakers then receive line power in daisy chain fashion from this breaker, and are connected to ac unit 1 and the ac water pump. None of the breakers tripped, but eventually the daisy chain connection to the second circuit breaker burned through so ac unit 1 and the ac pump no longer received power. Ac unit 2 continued to operate. I ohmed out the compressor on ac unit 1 and it checked out good.

A couple of questions because master boat electrician I am not. Because this happened on the line side, it seems to me this was caused by a loose/corroded connection of that wire to the line side of the circuit breaker. I plan to rewire and then check to see if all is well. Also, plan to replace that breaker when I can locate one (boat is a 95 and in a quick search I didnt locate a readily available replacement). Are there any other possible causes or concerns I should consider?