Magnepan ribbons problems

I've been using a pair of MG3.5 since 9 years, and though they've been performing superbly, I keep getting ribbon rupture problems. Due to the lack of local dealership, I've been doing the repairs myself, using their repair kit, but has anyone else encountered such problems ? I need to change 2-3 ribbons every year.

One of the speakers I'm considering upgrading to is the MG20.1, but I'm concerned about the tweeter. It's a right pain in the neck to change it.