You should be able to disconnect the shift cable at the throttle/shifter quadrant, and operate the shifter to check for binding. If the shifter is OK, then you might reconnect the cable to the shifter and then disconnect the back end of the shift cable at the outdrive. This should isolate where the binding issue is. The parts catalog at
www.Fourwinns.com should have the part numbers for the shift cable and the throttle quadrant. Look also for the part number that is part of the part's name. This is usually a Teleflex or other brand's part number. This can be used to help identify the parts you need. Your Four Winns dealer should be able to get these for you. Otherwise, you can get these under a Teleflex or other part number from retailers such as West Marine, or online at ebay, amazon, etc. Shift cables should be in the $50-100 range.
The Four Winns Parts catalog shows "041-0298 CABLE, CONTROL 17' CC17217". The "041-0298" is the Four Winns part number. The "CC17217" identifies the cable manufacturer's part number and the cable end connection style and size. "CC172" identifies that both cable ends are a male 3/16 fine thread (or 10-32). The 17 at the end of this number is the cable length measured in feet. The shift cable is 17 feet, and the engine throttle cable is 16 feet.
If the throttle quadrant is bad, repalcements may be in the $250-350 range.
Hope this helps.