You don't need to remove the pumps to do the first round of troubleshooting (unless they're installed somewhere with limited access).
Start by removing the cover plate off the pump head, which will give you direct access to the impeller. You can then slide it off the shaft directly towards you. Once you've got the impeller out try the pump again, if the shaft turns then the impeller was bound up (which can happen for a number of reasons). The simple solution is to replace the impeller. Like someone mentioned, if your impeller is black, I would absolutely upgrade it to the new green compound impeller
(I would probably upgrade even if your existing impeller is yellow).
If the shaft doesn't spin and you've confirmed the pump is getting power then it sounds like the bearings are seized, which is not good. If that's the case, your only real option is to replace them.