sparking starter bendix

[cobia81]

I replaced the starter on a 1990 40 hp yamaha 2 stroke a month ago.It worked great. yesterday I noticed that when i tried to start it it almost sounded like the battery was weak but it still turned the flywheel and ran fine. when i went to resart the motor it wouldn't do anything but the selinoid would click. I used a test light to see if the selinoid was gettting power and it was. checked the grounds all good tight and clean. When I used a jumper wire on the selinoid hot to the starter power wire, the starter worked but when the bendix engaged the flywheel it looked like a sparkler. I took my test light and checked the bendix for voltage when starter was engaged. The bendix and I guess the pinion shaft both have voltage when the starter is engaged and when it touches the flywheel which is a ground it sparked very very bad. Is it a bad starter? confused only a month old. The bendix reads a ground when no power going to the starter, I thought it should always read as a ground? Anyone have this problem or more knowledge please help, thanks

[boats.net]

Sounds like starter is not making a good ground connection to engine block.