There are a few anti chain suck devices out there, Lapierre make a specific one for Bosch. I have one, but not fitted as winter is not here yet, I got it from Race Co in Stourbridge, but stock is always very low or non existent
I am also waiting for a new bosch motor, the turn around is usually only a few days, but I believe last Monday was a Bank Holiday in Germany and everything fell behind. Still no excuse, I wanted to be out on mine the weekend too
The Warranty process for Bosch has really improved now that Magura have taken over the claims process. All you need is original sales receipt and the claim will go through quickly, the longest part is usually for the motor to be posted. Shipping can cost about £60 but hey you get a new 2 years...