Repairs 10323 Crankshaft pulley and set screw access -- Disassembly question

First time poster. Got a 2003 Model 10323 from a friend. He was frustrated as the self propel was not working and he was using as a push mower. When I got it and started it, there was a loud clacking sound coming from under the engine. Eventually, the clacking stopped but now the pull start is very hard. I am able to turn the engine over quite easily by spinning the blade so the engine itself is not seized.

I suspect that something wonky has gone on with the crankshaft pulley and set screw (I tried other adjustments for the drive prior to this pseudo lockup state). My question is....how much disassembly will I need to do to get to those? Do I have to completely remove the engine?

Thanks in advance for your help.

Yes,you have to remove engine to work pulley.Many times set screw just sheer off.