Oldwild,
Thanks for posting the link. I'm going to take the saw apart some today on my day off. I've read on the chainsaw collector's website the model 500 is supposed to have a walbro carb, and I've seen the walbro name on my carb, just not any numbers that make sense. I've got to find the source of contamination that is blocking up the fine screen in the carb, makes it lean on the top end. I'm thinking that the in-tank fuel filter needs replacing. While I had it apart again, I was going to get a gasket set, I just want to get the correct one. I'm also going to switch to a different batch of premix, the old stuff may have to run out through the lawnmower!