If your talking about the positioning lever and not the engage lever.
what i do when mine sticks is to engage the pto at engine idle. then
move the pto positioning lever as i disengage the pto. The whole set
up is pretty cheaply built on the bx models. If it's the engaging lever
try turning the pto shafts by hand then engage it. With the tractor
not running of course. Only thing i can think of.