Getting the slipper assembly in & out : is there a knack?

[colmo]

I ran my BJ4WE last night, but had to replace the spur as the motor came loose and shredded it.

It was a bugger to get out, and a complete nightmare to get back in (very little time between heats!) - I ended up running my B4 in the 4wd final as a result.

Is there a trick to doing this job more easily?

Also looking at ball ended drivers for getting at those accursed motor screws (blocked by the battery posts...argh!)