Just got a lazy boy 3.5hp tiller, know nothing about it, gas?

If the gearbox has oil/fluid and the level is correct, I would dismantle the shifter, clean and lubricate it with dry lube. Using oil based sprays, WD etc, will cause a dust/grime build up and make it jam up again.

open gear box and inspect /adjust linkage

Check this post hope this might help you.
https://homeztale.com/lazy-boy-recliner-troubleshooting/

Cheers!

Use https://www.google.com to search for vendors, and contact them to verify correct part.

Example from Google search:

https://www.smallengineequipmentparts.com/brand/lazy-boy

Small Engine Equipment Parts LAZY BOY Parts Catalog

Small Engine Equipment Parts LAZY BOY Parts Catalog Might try here.

www.hyperparts.com/ope/LazyBoy-oem-list.htm

ITs not really a lazy boy brand is it? If we a re talking about garden tillers... then if the fill hole is on top the oil level should be about 1 ( one) inch below the hole. If the hole is on the side of the gear case then it is a peep hole and should be filled till fluid runs out.

I have located a great article that explains how to properly care for your Lazy Boy recliner to keep it looking nice and ensure that it will last longer.

http://ezinearticles.com/?How-to-Clean-Your-Lazy-Boy-Recliner&id=1829676