Stuart Firth
My experience of these is that they always stick solid when first tried. The first thing is that the slots the tabs go into are quite slim, so the act of pushing the tab into them can expand the metal slightly outwards. If it does then gently file it back straight. After this point I always adjust the block to fit the the guide – as John says, a few light strokes each side, then test, so on and so forth. It should be loose enough to fall under its own weight but not so loose that it can move back and forth. Finish with very fine wet and dry paper to get a really smooth finish. It’s very important to mark the bottom of the bearing with a scriber so you always put it back the same way, partly because once you start filing it the hole may no longer be perfectly central in the block, and partly because it sometimes isn’t anyway! If you always put it back in the same orientation then this doesn’t matter and will be taken into account when you install them using axle alignment jigs.