Well, not really jammed but two instances I experienced myself.
First solo on Gazelle ;-)
Took off and set forced trim for acceleration. And then I had a problem.
Radioed my instructor and did a short circuit to land.
By the time he got to me and jumped in my muscles already ached.
I warned him - and he was still surprised about the forward force, when he said:"I have control"
We flew back from the training to the main airfield, changing control in-between.
Back at base a technician came out, had a short look and pressed a circuit breaker back in......
Second incident - on BK117.
We had to change helicopters.
When I jumped in as Co-Pilot in the already running return helicopter I used a well trained technique,
moving my right feet over the seat. (I have fairly great shoes, so its safer than fideling it between stick and seat)
I went through the pre take off checks and shortly after take off, I said to the pilot - we have to go back.
He looked with a big question mark on his face and his eyes followed my finger, pointing to the stick - still - he didnīt caught it at first.
Then he saw it as well - the stick was installed front to back - the notch/bend in the stick, through which you can fidel your foot to get in - pointed backwards toward the seat.
Imagine, the seat not totally back - and flying solo - that would have restricted the movement.
as always PPPPPP (proper preflight prevents piss poor performance) ;-)