A fluid change would definitely be in order. The Dual Range transmission was pretty rugged, but it's very picky about throttle pressure, controlled by a piece of linkage from the carburetor to a bellcrank on top of the sheet metal cover on the driver's side of the transmission. Also be aware that "Park" on that transmission is engaged by selecting Reverse with the engine not running. If you're going to do any towing, or even pushing the thing onto a trailer, stay out of Reverse.
The original transmission fluid used in H-M was "Type A Suffix A" which had an interesting ingredient- - - -whale oil. Dexron is supposed to be a suitable substitute, since OEM fluid hasn't been available for decades. Definitely don't use "Type F" or any of the high performance fluids,. since they have more friction enhancers, and the H-M shifts are pretty firm to begin with. It definitely doesn't need any help in the clutch lockup department!
It's not uncommon for lip seals to dry out after long periods of inactivity, and the front seal on the Dual Range is a royal PITA to change. If there's any leakage at the bellhousing after startup, bite the bullet and find an oldtimer familiar with repairing one of these units. We're getting progressively harder to find, since the last Dual Range I'm aware of was installed somewhere around 1956.
Jerry
