Hi RJ sutton

This link points to a 12v DC servo motor search.
Some of these units have an integral gearbox while others don't however if you make sure the shaft and flange mate up many will will work with a separate often right angle gearbox. Servo motors usually have an integrated encoder.

Leadshine offer a good range of servo controllers.and or motors. They are blatantly copied! and it is hard to tell the fakes are so similar. Make sure you are getting the genuine article.

You will need to control this setup with a micro, an Arduino for example.
This approach using servos better quality gearboxes and a dedicated controller will cost more but it should be very long lived and reliable.


Regards
John

https://www.google.com/search?q=12v%...%3Apinterest.*

Worm reducer search

https://www.google.com/search?rlz=1C...4dUDCAY&uact=5

Leadshine servo controllers

http://leadshine.com/Pdf/Catalogs.pdf