Yes the Silo was a pretty cool design but the plug igniter contacts required much more up-keep and care then most wanted to put up with.
Shortly after these systems were introduced back in 1999 I retrofitted my silo's with standard micro clips on a self supporting wire coil to allow any size or shape Micro model to be flown from the same Launch rod hole. This system worked very well and is still used on occasion or when I give a silo system to a new Micro modelers, family or friend.
Over on the MicroMaxRockets yahoo group there are step by step instructions for this conversion and adding a 12volt direct drop battery connection to the 9v hockey puck or new Hand held controllers. NO other alteration to the controller are needed to use with any 12v battery.
As Jeff mentioned if you want to talk to anyone about the manufacture of MMX Motors it's best to contact Quest directly. Personally I'm looking for the next run to include a TRUE MMX-II-0 Booster motor instead of the after market MMX-II-NE we now have.
As far as Kits and parts there are a number of GREAT sources for Micro Maxx Kits and EXCELLENT Parts Fliskits being NO#-1. Quest recently also started offering some of their own MMX parts though limited in scope.
You might want to join us over on the Micro Max Rockets yahoo group. We have Tons of info, Plans and parts sources for everyone's use.
I'll see if I can upload a pic page of the silo conversion but it will likely be kind of hard to read.
With over 190 different Micro Maxx Models in my fleet at the moment I certainly don't want to see MMX motors discontinued but it's all up to all the MMX flyers out there...If we buy motors Quest will keep making them... if not?