Question........Has it simply quit peeing or is it overheating????? To test for a stopped up pee tube (simply a indicator), start the engine on the water muffs. If water is running out around the prop after running for 15-20 seconds, then the pump is working. But still need to be changed.
That is going to be a Yamaha made Mercury. The linkage on it is a turnbuckle and pretty easy to do especially if he is a auto mechanic. Usually when the pump has failed, the impeller has come apart and some of the and pieces are shoved into the engine and will cause problems later on when they plug up the water passages.
Feel free to pass on my number and I will be happy to explain how to remove the lower on it or pm me his email address and I will send him the section out of the factory manual in PDF on removal of the lower and replacement of the pump. emoToast emoToast