just a thought...
do your boots actually
close easily?
Or do they often need a really firm smack?
My thinking is:
If the rubber bungs are screwed out too far, then this can lead to the "won't shut easily" problem.
However, once shut, said bungs would be (possibly) forcing the D on the boot up dead tight against the latch part of the lock.
Which might then be putting it under too much strain to be able to open.
I
could then also be leading to a bigger than expected gap around the boot lid, leading to the seal not sealing, and letting water in.
This is of course all in theory, and could be something which the dlr should spot...
But it wouldn't show up on a diag computer screen...
