Yes, "sticky throttle", one of the troubles a TB can suffer.
From the earliest start on, I did not only exchange the potentiometer cap for a contactless one, but gave the units a complete overhaul, including the magnetic rotor clean up and reseal.
That reseal however, proved to be the part that caused some problems over the years.
Funny thing is, that some units that come in, show a perfect and undamaged aluminium factory seal, others are completely desintegrating.
These desintegrating rotors, are quite difficult to clean up in the first place and then reseal in such a way, that desintegrating does not show again.
Now a very solid and durable solution is used for some time already.