I wouldn't thump it on a hard surface. If the heads aren't parked that would probably slam them into the platters.
I contributed to the thread you're talking about and what I do is put a few drops of 3-in-1 down the spin motor spindle with the drive spindle side up and leave it for a few hours.
Then gently move the motor by hand very slowly counter-clockwise about 1/2 a turn.
Power it up and if it spins, let it do so for an hour. If not, give the spindle a little push with a small screwdriver (again, gently) to get it going. After an hour, turn it off and leave it for a couple of days (still spindle side up) and then power it up again to make sure it will spin up on its own.
I've never had this fail.