Gear Head Motors by Lynxmotion

Hello, does anybody have any experience with gear head motors sold by Lynxmotion, more specifically GHM-04 and GHM-05? The GHM-04 has an
external motor shaft for adding USDigital Encoder. Do you have experience with this encoder? Has anybody tried to use the USDigital encoder with GHM-05 or any motor without the external motora shaft? I would like to know whether it is possible to hack the motor without the external shaft to be able to attach the USDigital encoder to it. Any information is appreciated.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
Add image file
Upload is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.