I've a G923 Logitech. The funny thing is that I had the same issue last month at Tokyo Gr.4, but on the throttle and in an opposite way like vibrating between 0% and 40% when released. So the car was "pushing" while braking. It went on 2 days, then stopped. No problem after 1.52 patch recalibration, so Spa and HSR went very well, till last Friday with an undriveable car at Spa and very bad feeling at TM. I'll need to check the potentiometer and alignment of the mechanism, maybe also find a way to put a much harder spring to have a less "spongy" behavior from the pedal. Still, it's an entry level solution. I'll buy in future an used Fanatech from someone that purchased it just to use it maybe twice and make it just accumulate dust. In Switzerland it's easy to find deals like these.