Might be helpful if you posted the model number of the engine. 12 year old Craftsman doesn't tell us much.

You need to do some more checking. Does the engine turn over OK with the spark plug or plugs out? Does it have a good battery? Are the battery connections good? Just for starters.

Walt Conner

I have a craftsman v-twin and the starter just
absorbs current and does not turn over the motor.
I let it sit for 5 years. The motor is free.
The starter is seized from moisture induced rust on the
windings spacing.
Not sure if yours comes off with the 2 bolts to the
crankcase or not.
Mine seems integral to the housing, and I had to remove
the two looong bolts that hold the lower plate on the
starter.
A LOT of PBLAST and some taps of the plastic gear
with a mallet and the starter freed up. But the problem
is in reinstalling the 4 brush plate and holding all
brushed in to get past the rotor.
You can fied test the starter on a bench with 12 volts.

***" But the problem is in reinstalling the 4 brush plate and holding all the brushes in to get past the rotor."***
That part (referred to as "rotor"), is the commutator (in case you do try taking the starter apart). There are a few threads throughout this forum that include some methods for "keeping the brushes caged" during assembly. If you are going to attempt a "teardown", I suggest you research the older forum threads for these tips and techniques.
***" You can field test the starter on a bench with 12 volts."***
Yes, but not "just any" 12V source. Ideally you need to use a 12 volt automotive battery, at least as "big" as what is in the tractor, and that battery must be fully charged. Trying to use a small, low output battery charger will likely produce negative results. Use a set of jumper cables to a "known to be good" 12V battery for bench (or "driveway") testing.