Hello Erick,
The fact that your starter spins means that the solenoid most likely is good. The solenoid must retract to engage the contacts for the starter to spin.
The starter drive, sometimes called bendex, is the ratcheting drive gear which is probably failing and the cause of the spinning. The drive is not locking and allows the starter to spin freely. This problem is often aggravated by cold temperatures. Lack of use and the accumulation of surface rust on the starter shaft is another remote possibility, however if this is the case the problem may fix itself after a few starts.
The problem may take a while to become critical as the frequency of the "spinning" increases over time.
An automotive electric shop can replace the drive. A complete exchange starter unit may be the more economical. You may just want to try it yourself, or find an era sedan starter to experiment with, they are nearly all the same.
Joe Alexander
Blacklick, Ohio
