hi rosco,
only a guess , but i think you may be missing a couple of springs, ive had both rancher & ranger models , & when disconnecting the cutter drive you pulled the deck against the spring tension , & when engaging the drive the springs take over & thus tension the drive belt . you will need a rather strong spring force (trampoline springs perhaps )if you can not come up with the correct replacement part . if you are still in doubt i will be available for further suggestions , cheers,
john.

i may have retired but i havent stopped yet, ive got one shed full of woodworking machines & hand tools(my other love, makin sawdust)my othr shed is mechanics tool chests stick &mig welders metal lathe 9 inch swing screw cutting so if icant buy it i make it,i hope im writing this in the right place,thats all i can think of at the moment, cheers & beers