Speaker Component Sources & Suggestions?

I have a pair of Mission Cyrus Mini-Monitors that I would like to repair. The original mid-bass driver broke and was replaced with another cheaper unit through a dealer (took 6+ months but that is the topic for another thread). The replacement broke very shortly after installation. My thought is that the crossover is in need of replacement. Also, the mid-bass unit will need replacement again. The tweeter seems to be O.K. and sounds quite good considering the age of these speakers.

The mid-bass is a 5-1/4 inch unit. Any suggestions for a reasonably good, inexpensive replacement. The speakers were originally 6 ohms. Does this mean that the replacement driver should be 6 ohms?