Martin -
A while back I posted what I did as a workaround to this problem in your "Houston, we have a problem!" thread. I've cross-posted it below in case you didn't see it. I currently use my parking brake as my brakes by mapping it to a button on my yoke. Not great for tight turns, but it stops me.........
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Made a bit of progress in my issue of planes not moving down the runway after application of full throttle. Based on what I read In another group, I removed the bindings for my left and right brakes AXIS and changed them to left and right brakes (NOT the axis). Although I now no longer have brakes (not sure why), I've been able to take 15 flights with no problem in taking off or getting the plane to taxi after coming to a full stop! Before this my plane wouldn't budge 9 out of 10 attempts. I'm trying to figure out what this means, but am enjoying flight again! Prior to this I'd disconnected all my peripherals one-at-time with no positive effect and I checked for duplicate assignments with the wheel brakes and parking brake. Didn't see any problems with overlapping assignments. Not sure I'm any closer to understanding what the root problem is, but maybe the AVSIM braintrust can offer some suggestions.