front derailleur

[crackers]

I'm having trouble shifting to big ring, I keep adjusting it but pretty soon the chain starts rubing then eventually it won't shift., this can happen within one ride, iv had the lbs adjust it for me but the same thing happens. Any advice please

 

[Mobytek]

Sounds like your shifter does not hold when the pressure of the FD sping pulls back on it.

are we road / hybrid / MTB. doube or triple ring, Shimano /SRAM etc, make and model?