Here's a link for Bennett's actuators -
http://www.bennetttrimtabs.com/catalog. ... 8&techID=9
If you click on "schematic", (pdf) and scroll down, they mention that 2 1/2" travel is standard. So what your seeing sounds about right.
Never seen an actuator itself get stuck. The tab (plane) maybe, but I think it would take years of sitting idle, accumulating a lot of rust/crud. The plane and the mounting plate have a fold, (crease) that over-lap each other, forming a hinge. They're also pinched at each end to prevent "slide-out", but there's plenty of free-play, so normal rust, growth and even paint build-up shouldn't restrict them. If there was damage, that somehow pinched another area of the hinge, that would be a problem, but it would only effect that one tab and the boat would lean.
In any event, the best way to check something like this, is to have the boat out of the water and observe the tabs while someone else operates them. If the planes are jammed, you can disconnect the shaft, (bottom of actuator) from the plane, remove the backing plate from the transom, and clean them up. Make sure you re-seal all the mounting screws.
Besides that... you might have a leak, so check the fluid level in the pump. If it were low and had air in the system, that would allow the actuators to retract somewhat, while under a load. Check the line connections, (pump and actuators) as well as the cylinder area itself... again, while someone else operates the tabs. I've seen leaks right at the top of the acutator that simply required tightening the cylinder, (clock-wise) by hand.
Anything different from the other times you used the boat? Were your motors trimmed down all the way? Any changes in weight... people on-board, seated at the stern? Rear fuel tank full, front tank empty?
