Early Variable Wiper Motor

Yours might be fixable with a gear and gasket package. Had a similar issue with mine. Turned out there's a nylon or plastic gear inside, and some of the teeth were stripped out. Easy fix if that's your problem.

NOS Mopar 1957-65 CHRYSLER Windshield Wiper Gear & Gasket 1879 598 for sale online | eBay