I have repaired plenty of tanks and found a one sided razor blade the best thing. If you have any doubts about the silicone I would take it all apart, clean with meths and start again. The sliding door tracks I have obtained from hardware stores--one for the top and another for the bottom. They were pretty long lengths I had to buy so not easily posted. Do you have a decent hardware store in Naseby? Might have to get the tracks couriered from civilization.