Hi dmitr
I don't know how good your decompressor is ,I would remove it and put a spare spark plug in the decompressor hole,
then try and start the mower at least then you will feel the compression when it turns over.
Make sure the blade plate is tight to the crank but if it's not kicking back on the starter it should be good.
Just in case the carby primer isn't working ,take the spark plug out and pour a small amount of fuel
into the plug hole before starting it should run for a few seconds off that fuel if there is a carby problem.
Take one kill switch wire out off the carby when starting in case it's shorting out from movement.
If it almost starts take the plug out to check that it's not wet ,if it's flooding the wet plug stops it from starting.
Cheers
Max.
