I have purchased four removal keys so that I can take out my RNS-E unit for servicing. Tried the first key (behind the motorised screen) and found that it will go in, seems to be pushing against a spring, but it does not 'click' nor lock in place. I expected it to lock onto the fixing spring clips and then when the RNS-E was out one can release the spring behing the front panel. Have not dared to push the other three into their slots in case they do lock-in and I am left with one that does not. Does anyone know if these keys do lock into place, or if they do not always lock, they still have moved the mechanism to allow the RNS-E to release and move forward? If the keys do lock, can they be removed with a strong pull? Hate to be driving around with removal keys sticking out of the RNS-E. I guess my keys may not be the best (eBay), so are there some really good keys to be found? Thanks for any help and suggestions.