What are a usual measure between the diameter of the inner tube (shoe) and the inner diameter of the outer slide ? ..Are 0,25mm Ok ?

Trond

0.25 mm (approximately 0.010 inch) should be "tight" but OK. There will be little margin for misalignment of the slide. From a strictly "clearance fit" point of view, it's a good "running clearance" allowing good movement. But get a slight bend in the slide and you will have something that really doesn't move well (if at all).

I'll leave it to the techs who live with it to describe what they do.