Hose Reel
Is there some trick in slipping the leader hose over the?
Fitting, it is then secure with a hose clamp. You will notice the fitting
Has a ridge. Hard sliding it over the ridge.

If its cold (even if its not cold)... warm the end of the hose up with a hair dryer ( no need to do more than 4 inches of it) . Wipe some dish soap over the part you are slipping it over as well as inside the hose. See if that works for you.

I used to boil a small pot of water, submerse the hose end for a while and push over the ridge.