Checking a non running outboard

[theoldwizard1]

I found what looks like a good deal on a 70 hp Johnson (no year) on Craig's List. The ad says

Hasn't been in the water since last summer after being locked in gear.

Further inquiry got a similar response

Does not turn over as it is not in neutral. It is locked in both reverse and drive

Is there anyway to do a compression check and determine if the problem is really in the lower unit or is it a blown rod/piston without completely removing the lower unit ?

 

[Bosunsmate]

nope, you would want to drop it too so you can check if the spines on the bottom of the crankshaft a damaged too

 

[Chris1956]

Bosun is right. Any idea if it is electric shift? I cannot tell from your post if the motor is locked up, or just stuck in gear. Any idea?

 

[Tim Frank]

That's what OP is trying to determine.