The Porter Cable 7301/7310 trimmer motor has been discontinued and is no longer available. You may be able to have motors rebuilt at a DeWalt Service Center or small motor repair shop.
The Castle TSM-21 is now built with Bosch motors. Please see part #K21123 for the Castle TSM-21 Conversion Kit. The kit includes a motor carriage and both the Bosch Router & Trimmer motors plus the 3/8" collet.
Specifically engineered for use with the Castle TSM-21 and TSM-12 line of Pocket Hole Machines the E27301 Trimmer Motor PC# 7301 Assembly is a spare part you need to have. Engineered to hold up to heavy duty use of an industrial environment. Keep one on hand for a quick change in order to keep production steady. Please contact us with any questions you may have or application questions.