I have a motor caravan on a Peugeot "Boxer" 2.5TD chassis, circa 1996. The gearbox has recently been replaced. Now, if after driving for some miles and while in 5th gear I brake it becomes impossible to disengage 5th gear unless I either accelerate rather than halting or, after halting, I wait for some time before pulling vigorously on the gear lever. As an alternative to the latter, if I slip the clutch while revving the engine to get moving again, once moving I can disengage 5th and select the appropriate gear.
Have you any idea as to what could be the cause?