Help with Poulan Pro Trimmer Cap Replacement

I need to know how to remove the cap assembly from a Poulan Pro (PP031) curved shaft, gas powered trimmer. I wore through the old bump style advance part of the cap assembly and the local stores do not carry parts anymore. I bought a different brand part and need to take the old one off to see whether it fits or not. Any help would be greatly appreciated.

 

I'm not looking at a diagram, but doesn't it have flats just above the head to put a wrench on it? If so, put a wrench on it and unscrew it in the reverse direction it would rotate when the engine is running.

 

A curved shaft trimmer will have a standard right-hand thread and therefore you will turn it counterclockwise to remove the bump knob.

 

The problem is that at the end of the curved shaft and before the cap assembly, where the nut is that is used to unscrew the cap assembly, the gap has somehow been narrowed to the point that a wrench will not fit in the gap to unscrew it. I have tried beating on the cap assembly with a rubber mallet to try and increase the gap, so I could get the wrench around the nut, but to no avail. Any other suggestions...

 

I'm thinking that you have somehow lost the dust cup (part number 530094543) or the trimmer head is so beat up that it has distorted and is actually now hiding the dust cup. The dust cup is a rather large hex nut that is unmistakable and uses a 7/8" wrench, or so, to grab a hold of so that you can remove the bump knob and/or the entire trimmer head assembly. If this is missing, as opposed to hidden, then I've had luck using bicycle wrenches to get a hold of the smaller hex nut behind the dust cup. Bicycle wrenches are very thin so that you can get into tight areas or, as designed, the thin, jam nuts that are common on bicycle axles. Check with one of your local bicycle repair shops for such a tool.