I removed an old rusted clutch last night. Apply heat to the end of the crankshaft, after it gets warm/ hot, drop some light oil on it, which will get sucked in. I use 10W30 synthetic oil, it doesn't smoke when it gets hot.
For heat I use a heat gun, puts out 900 degrees air temp, used for removing paint, readily available and cheap. Looks like heavy duty hair dryer.
After oil has penetrated, screw in the retaining bolt with approx 1/8" space between the clutch and bolt. Use a long handled screwdriver as a lever between the inside of the clutch and engine side plate. With pressure applied to the screwdriver, wack the head of the bolt with a hammer.
Like was pointed out above, don't use a lot of force or you will damage something. Just keep re-applying heat, oil, use screwdriver as lever, wack with hammer and it will come off eventually. :thumbsup: