Evinrude Stuck in Forward

[Bassmaster]

I need ideas of where to start. I have a small bass boat with a 50HP 1987 Evinrude VRO. <br /><br />Was out fishing last weekend, fired the engine up to move to another spot. Shifted into forward, started a slow acceleration to WOT, and after a few hundred yards on plane, heard a sharp, quick "pink" sound.<br /><br />The engine rpm or the "felt" power didn't miss a beat. Stopped to fish another spot, and when I fired up to leave again, the gearcase is stuck in forward gear. It powers forward when I lift the idle arm and/or when I shift to reverse and apply throttle.<br /><br />I checked the linkage, all the way down to the shift rod (which can be seen entering the gearcase under the steering assembly), and it is moving up and down. So I expect the problem is actually in the gearcase.<br /><br />Does anyone have an idea of what could have failed, considering I was already locked and cruising in forward? Is it time to take the gearcase apart, or is there something else to try?<br /><br />Prior to this, I never had any problems with this engine. No impacts and always took good care. However, it is a 1987 engine and I am the third owner. I did replace the original stock prop with a stainless Powertech prop 15-20 running hours ago.<br /><br />Thanks