I also learned the hard way. I also think that the need to exercise may not be as critical with fuel-injection equipped generators.
In Dec 2011, I needed an angioplasty and ended up with four stents installed. I'm fortunate to still be on the planet. During my convalescence, the generator monthly exercising dropped off my radar screen for 5 months. When I finally got to it in May 2012, it wouldn't start, and, despite repeated attempts to trouble-shoot, hasn't run since.
We're FHU campers, so it hasn't been an issue so far, but we will need to get it fixed before we put the rig up for sale in the spring.
I've replaced the fuel pump and all fuel lines from it to the carb. I've also soaked the carb in SeaFoam to try and remove any varnish deposits. It will prime and crank, but it backfires like crazy and spits our big gouts of white smoke, then quits. White smoke usually indicates an attempt to burn coolant, but this thing's air-cooled!
I've worked with engines for a lot of my life, including a couple of years working for Norton Motorcycles, but this POS has me flummoxed.