I bought small linear bearings KG LME 12UU. The reason I had to buy these is that the previous pair I bought, one of them the retaining clip/seal holding the cage inside the bearing came adrift. The bearings and the cage all fell out and then got squashed in my guillotine causing the metal to have ball shaped pit marks. Not that many cycles - about 3,000 of less than an inch reciprocating. I've replaced the one that disintegrated but I notice that the seal on the other one is not tight, I can rotate it? It's only a small machine that chops 'keyloops' www.keyloops.com Not under much stress - so I don't know why the KG bearing failed at such a low usage? Your feedback would be appreciated. Thanks, Alex