John Kalmbach sent me an e-mail in which he mentions that "...the fuse is actually a 6 amp auto-reset circuit breaker with blade terminals that will fit into a typical ATC fuse location (inline or panel mounted). That is why the cost is so high."
John goes on to say "While there is not an easy way to lower the PH top if there is a mechanism or motor failure, most failures occurred when trying to raise the top and there was a load on the system. So, you are not stuck somewhere with a top that won't come down."
That is the situation I was concerned about...too much load and popping the circuit breaker. John did talk about how the get the top up in post #:
Of course, I didn't pay that much attention to that post back then since we didn't have an electric penthouse at the time...