Try Power Blast aka PB Blaster. Spray the offending area, tap it a few times with a hammer, and let sit. Repeat several times a day if possible for a week, then try removing the plug. Warning: Power Blast has been known to melt things not made of metal.
On another issue, I'm impressed that your engine cranks with the amount of corrosion showing on your battery terminals. You need to apply some serious elbow grease to that engine's rust issues.
Straight drive is one straight shaft running from the engine aft to the propellor. A vee drive runs initially from the engine towards the bow, then forms a vee and goes back to the prop.
Sail Fast Live Slow
40' Norman Cross trimaran
Last edited by FSMike; 03-10-2010 at 06:16 PM.