Jeff - I assume you are referring to a throttle lever that looks like this:
![[Linked Image from j30.us]](http://www.j30.us/images/Backstay-Aft-Cheek-Blocks.jpg)
It is probably fused in place if it hasn't been lubed. Remove the lever from the bulkhead and disconnect the cables. Disassemble the entire assembly and make sure you don't loose the spring and ball bearing that acts as a detent. Clean all the parts get all the corrosion off the rod that goes through the center that the black knob screws into. This must be lubricated well with grease when you reassemble.
You'll see when it is apart how the black knob engages the shift lever or disengages so you just move the throttle cable. The throttle cable moves the same direction when you increase throttle position in either forward or reverse.