Problem with assembling suspension on Tamiya Pershing 1/35th kit (TAM35254)

Hello folks. I must be missing something really obvious, but try as I do, I cannot get the outer wheels to stay on each axle (I've been stuck on this task for over an hour (I'm guessing I am not working 'smartly' enough). I am using the small polycaps: Each inner wheel stays snugly on the axle using the small polycap, but each outerwheel just flops off. No amount of jiggling, pressing the wheels together, etc. succeeds for me in fastening the outer wheels (they are simply nowhere near snug enough to stay on). What connection (cognitively) might I not be making here? I'm hoping someone else might have run into this problem and solved it, too... The instructions clearly state that I should not glue the wheel halves and  small polycaps together (implying that they should rotate (and stay in place) without gluing; but alas, I don't really see any alternative to doing so...Grateful for any insights. Many thanks!