Belt sander marks

[Lazurus]

never had a problem with my Wolf belt sander but last couple of uses it is leaving marks on the timber surface as though I am not holding it level - perhaps it was user error, anything I should check?

 

[MikeG.]

Sometimes there is a graphite sheet under the belt, and if it wears away at the edges you can actually just be pressing the belt down with a piece of steel, giving you a chance to leave marks. So check that. Or, check that you aren't sanding in a hollow.

Other than that, don't press so hard, and don't be in such a hurry.