I hear a few people say they prefer the older Victa carby because they don't understand the G4.
The newer diaphragms are made to move a lot better than the old flat diaphragm ,if I didn't hold the poppet out when fitting the back cover with the flat diaphragm it had no slack in the diaphragm to move.
Another problem is when people mix and match parts ,seen the wrong poppet valves used a few times (the poppet for a Vortex used on other mowers)
