Do you have the side firing 10"?
You say you had two amp failures? In both cases was the failure on the channel powering the same RM30? Compare the input resistance of the bass sections alone, one RM30 vs. the other RM30. If one measures lower, on that speaker, remove the woofers and make sure the terminals do not short. It was many years ago, but they employed thick wire soldered to thin driver terminals, which combined with the thick baffle, bent and shorted the large wire/solder lumps of one woofer together when they installed the woofer.
Hope this helps.
The minimum impedance may drop below 3 Ohms. What is your amp's minimum impedance rating? I'm suspicious your amp is not rated for low impedance loads.