Today i received my materials for building my 3D printer. It was very well packed! - thumbs up!- (unfortunately had to pay $39 customs duty on top the $50 shipping) When trying the delrin nut block on the lead screw, it does fit, but it's very tight! By hand i can only twist the block on the screw until the screw is starting to come out on the other side. Then my hand starts losing grip on the screw and i can't get it any further. Do i have to wear the blocks in in some kind of way (run the blocks up and down using a drill), should i lubricate them right from the start? (and if so, with what?) Please help me out?