Motor last ran in 1975 and has been stored empty of gasoline since. the thing is locked either in the lower unit or the cylinder head. Any suggestions to get it running again?

Drain the lower unit and see if it had grease or water or if it is dry. See if you can wiggle the prop back and forth a bit.

Take the cowels and gastank off so you have access to the flywheel. I like putting PB Blaster in the spark plug holes to soak and the after a bit try to rock the flywheel loose with a strap wrench.

Thanks, will do. Lot of sentimental attachment to this motor. Silly, I know but still......

Not silly at all. I think I bought 4 similar Elgins trying to get enought parts to fix my Dads 1946 2-1/2 HP Elgin. Some of the engine is from his original motor. I am sure even if you need some donor parts (even a whole power head) you will still be happy with your labor of lover.

Got motor freed up & lower unit checked out. Miracles still do happen. Now on to getting it running. Carb is cleaned. Thanks for your reply.

I am working on one at the moment myself. I bought a parts motor just in case as well. Let me know if you come up short on something or another.

I am just starting on WG4, serial no. 726497. It is frozen. I haven't ran it for 20 years. Does anyone know of a source for parts, like rings?
Thanks

Get rings here.
http://store.oldmercs.com/category_s/85.htm