If my days of owning HRC serves me correct, you can access the arm/handle mech once you remove the slot machine cover. Mine wasn’t smooth but I can’t for the life of me remember what I did to fix it when I had the cover off.
All I do remember is that getting the cover off and on again was harder than the actual fix. It’s tricky and I was very careful as I saw beforehand how much spare units were on Marco.
Good luck.