first off apologies if this isn't the right thread/forum. please let me know and I will move and/or post future questions to the group in the correct location.

First off let me say that I love this group. I got really into the Pla-rail system about 1.5 years ago when my son was 3.5 and he just wasn't old enough to not destroy everything. Now he's five and its a good old time. I am learning that I never though myself handy but dammit if I don't love taking these things apart, figuring out why its not working or why its so loud and fixing it and putting it back together. Of course we have a second 2.75 year old that destroys everything, just means I get to do more fixing!

Here is my question. I have some of these older trains. I get most of mine from ebay lots, craigs list lots or consignment sales. We have only bought a few new trains. I have some that 'slip' for lack of a better word; they run all herky jerky. at first I thought it was maybe a bent axle or something. Now I think it is the gear on the axle that engages the gearbox. on some of the trains it appears to have loosened. Before I ran off and started super-gluing the gear back to the axle, I thought I would ping the experts to get your confirmation. First, is my assessment correct (that the gear needs to be firmly on the axle, that the slipping isn't some intended feature)? and second, is superglue the best method?
Thanks,
BTW, SUPER, my son and I have really enjoyed your videos and mods.
Kevin