703 Control Problem

[Todd-d-Duck Hunter]

I just installed a 1997 Yamaha 80hp 2stroke. I purchased a used 703 "Push" control box and new cables to hook everything up. The control shifts from F-N-R just fine. The throttle works perfect in Forward. My problem is I have no throttle in Reverse. The throttle lever will not move when in reverse. Do I have a worn out internal part or have I reassembled it incorrectly? THANKS!