well...the first time I installed them - I had to force them in. On the next TZ I had, I was doing a shop job and had the gumball machine removed and installed them by taking apart the gumball machine. On my third machine...I forced them in (and I won't be doing it to a 4th machine - I finally found the keeper). I suspect forcing them in isn't the best way but it worked for me without breaking anything.