Semi-consistent Starter Problem

Hi, I have a 1992 Mazda B2600i 4x4, 4-cyl, 2.6L, 5-spd Manual Transmission, 300,000Km.

This truck is great, has been well maintained it's whole life. Recently (since 290K) it has developed an odd starter problem, and it seems to be restricted to cold starting. It did not do it very often in the summer, maybe twice, but as the weather is cooling, when I start the truck in the morning for the first time, the starter does it thing, but doesn't engage the engine. Rather it gives a moderate grinding noise, at which point I disengage the starter.

I try a couple more times with the same result, the odd try also giving a clunk (like it engages the motor briefly). After a decent clunk, the next try usually engages and starts the engine as though all were well.

This will go on at any stop (where engine is killed) until the engine reaches normal temperature and then will start perfectly every time afterwards (as long as it isn't more than 2 hours or a good cool off in between starts).

Any ideas? I thought missing teeth on the flywheel, but would give me the same problem hot or cold.

Maybe a sticking gear on the starter shaft, spinning before getting a chance to engage, and a few tries gets it moving enough to work properly?

Not a mechanic, but mechanically competent, got my manual and would like to fix this.

Thanks,

Scott