Re: Seized shaft removal 1980-7.5 hp Johnson
The easiest is to remove the powerhead from leg with the shaft.
Clamp it in a vice, power head down.
Then keep pouring all the funny mixes you get adviced to pour.
After some time, carefully try to knock the PH off the shaft.
However be aware that you might end up with a spline-less crank.
If you do not want to experience the latter, this is a naughty emergency way:
Cut the shaft about 1-2" above the water pump.
Weld on a socket on upper part, grind a square on the lower that fits into the socket. (3/8).
Be sure the total length of the shafts are the same as the old 1-piece shaft.
The above without warranty, but have rescued 'me' quite some times. Cheaper than replacing the crank.