Thanks for all your tips,
one additional question,
I have 3 blades, when I compare the level of blade A and B, they are ok
But blade C has a tiny problem :
I compare the level of blade C with blade B and Blade C is too high, I turn blade C 180 degrees (half a turn) and now is too low.
Blades are brand new, no use at all
I suppose the problem is not on the deck (because when I turn the blade 180 degrees the level changes from high to low) but on the Spindel/ shaft
any ideas?
thanks!
F