I have a 1985 4 cyl. 270 lower unit.The engine starts and runs, but output shaft only turns very slow in forward or reverse. Thats with the prop off and cable disconnected from the lever. (manually shifting) There was gear oil in it, but I drained it and put in 10w 40 as per the owners manual. Still same. Help would be soooo appreciated.
Pull the upper gear box off the drive and check the splined coupler that connects the upper and lower vertical shaft together. It or the lower vertical shaft may have sheered off.