Depending on which style you have – the drive shaft will come off by loosening the knurled nut at the top (directly under the powerhead). Unscrewing the nut allows you to pull the entire driveshaft assembly away from the powerhead. Then you can determine for certain if the powerhead is stuck, or if its the foot.
Personally I’d be surprised if its the foot that is stuck, on account there ain’t no gears of any sort in there, just the water pump as Harry says.
Hope this helps.
Best,
PM T2
He's livin' in his own private Idaho..... I hope to go out quietly in my sleep, like my grand-dad did..... and not screaming, like the passengers in his car...