RCREDD, i think you are right... the 1 pulse per rev wouldn´t have changed anything! I think i have now found out the real reason for loosing the steps... there was too much friction in the guides of the x-axis ( and i only lost steps in the x-axis), i forgot to put lubricant there and maybe the owner before too... for some years but now when i have pulled everything apart i will change the steppers anyway but i think it could have worked with the old ones... if the mechanics would have been alright.
Ok i have to admit that this was not very smart but we never stop learning