When I managed to get my heat valve to work it took many days.
Heat ........ spray with Bitron ..... soak ........ tap, tap , tap.
Heat ......... spray ........... soak ....... tap, tap , tap , tap .
Heat ....... spray .. tap , tap , spray .............. soak ............................................ tap , tap , tap .
Heat ...... spray ......... tap tap ta pppppp .......
Heat ,,,,,,,,,, spray ....... SPRAY !!!!!!!! ,.... wait .................................................................................. tap . tap . tap tappetty tap ....
etc
etc
etc ...........