drive belt tensioner...
 

Have the tensioner pulley and belt off (proceeding to water pump replacement...) but am wondering if the tensioner arm is seized? Is the arm something that I should be able to turn by hand? No prying etc? I have seen a great diagram showing the tensioner itself, etc. but have had limited luck finding a good thread if I actually need to replace the tensioner.
Thanks in advance.

The tensioner arm is very strongly sprung and you will retract it only with a spanner (wrench) when you install the (new) belt.
Removing the arm itself is more complicated and requires quite a bit of disassembly...
Use the search function (from member JFPinPA I think) for more details.

You can use 22mm or 15/16" wrench to push it clockwise.