Stihl BG75 blower just won't start!

Hi everyone, this is my first post and I've an issue that's a real head scratcher. I've got a Stihl BG75 blower, 2-stroke with nice fresh fuel in. It won't start, not even a parp, no matter how many thousands of pulls I give it. I've replaced the ignition coil with the Stihl oem one, new plug, new fuel and New air filters. Still nothing. The other day it ran brilliantly though? When turned over it seems to be getting fuel, as its blowing fuel out the exhaust that's unburnt. There is a spark, according to both my spark tester and the plug itself resting on the head. Not a bright blue spark mind, but on a sunny day I could still see it. The flywheel is keyed onto the crank ok too. I've pulled apart and cleaned out the carb, and the symptoms above suggest fuels getting in. There's a spark too. Just no firing up.
Any ideas would be most welcome, as I've made this blower my "Everest" 😞
Please help!!!! Could it possibly be compression/rings?

Stihl BG75 blower just won't start!