fitted mine no
problem, other than the old one being a bit siezed on.
cap fit over and clicked on and i thought ha those people on the forum are wrong, for once!
tried it.... POP!
i pulled the cap off, trimmed 5mm all round its base with a stanley knife, popped back on, and its fine.
works way way better than my old one.
had to adjust my front aeros as the passenger side one was coming to rest too low and hitting the wing every few wipes!
well pleased though.
all i can suggest for you is maybe you haven't trimmed enough off the cap if its still popping. compare it to your old one, its quite a lot larger!