Mercury 50hp 2 stroke starter issue help

Hi, I've been having some problems with my starter on my 50hp 2 stroke mercury outboard, it is a 1986 model.

When I turn the key to go start the engine, the first few times it works as it's supposed to and cranks the engine.

However, after a few times, the starter will make a "grinding" noise, and seems to stop spinning.

I've taken a video to see what is going on and it seems like the starter lifts up to engage the flywheel, then lowers back down only HALF WAY,

and the flywheel sounds like it "grinds" to a halt. It might just be the starter, but I don't want to damage anything. I tried to start the engine manually

and it was starting just fine. Can bad wire connections be the culprit? The engine's been sitting before I bought it and I refreshed the carbs and lower unit

seals before starting it, but haven't gone over the wiring. Maybe the connection surfaces are contaminated? But I don't see how this would cause the

starter to make a "grinding" noise, which would keep making the "grinding" noise if I didn't release the key. Doesn't it mean the power is getting to the

starter unit if it's operating? Why would it work the first few times and not when the starter "warms up"? Any help would be appreciated.

ALSO as a side note, I saw a "spark" when I released the key from the positive connection on the starter where it connects from the solenoid. I don't think this is

supposed to happen and maybe it has something to do with it?

Facts for you.-----Have the battery load tested ( even if new ), often a free service.---Clean and tighten all connections.-----It is easy to take the starter apart for inspection, lubrication , perhaps new brushes and ohm test.----Inspect it , don't rush out and order a new one.

I figured it out, it had been sitting for a while so the lubrication hardened up and sometimes it was stopping the starter from retracting back all the way. A clean and new grease solved the problem!

I only use oil on the Bendix it's less resistive and doesn't harden.