91 740 turbo with 250,000 miles. Mechanic recently recommended a transmission flush. I've just lost reverse when the motor is warm (works when cold for now). No ugly sounds. Thoughts anyone?

 

Unfortunately, the trans is probably gone... a flush is unlikely to fix that, but I'd try it before getting a new trans or throwing the car away... or if you are really lucky it may be something simple as a linkage problem but I doubt it. 250k without good maintenance, its time may ahve come.