On my clarke 100e,when gas bottle is turned on. Gas just goes straight out of end without trigger being pressed. Doesn't effect gas even when it is pressed. Any ideas would be great, as don't like wasting gas?
Sounds like the gas valve is stuck open? Give it a tap or two to start with, to see if it frees off. Do a forum search for 'Gas valve stuck open' for more advanced advice.
Only if somehow the gas valve piston has got stuck inside the block while doing the swan neck change. Open the torch and see if the brass pin moves freely - it could be stuck in the block. Try a drop of WD around the pin if the pin is stuck, before trying to pull it out try rotating it first to help the oil get inside.
But even if the pin moves freely, the valve can still be stuck inside the block.