Thank you everyone for the help. HandyAndy - Thanks for the pictures, I am a visual person, helped me understand how it functions.
Still struggling with getting the riser shaft loose, 4 hits with PB Blaster, struggling to remove the spring, I figured it simply would slip out...NOT
An interesting finding - when I was testing the riser spring, I was running the engine, to let it heat up. At first the radiator was cool, after about idling for about 10 mins, then the radiator became hot to the touch (which meant coolant was moving through the thermostat and the water pump is working). Engine was idling just fine. The temperature gauge got to the H, but the idle stayed smooth. It wasn't rough idling. I let it run another 5 minutes. I shut it off. My question now is whether the engine is truly overheating (need to find a way to measure the temp). The temperature gauge eventually returns to C. Will continue to focus on the heat riser issue, but am puzzled by what is happening.
