Go to an auto parts store and get a speedometer cable cut off a few inches (approx. 8). Get a large knob and make it as light as possible. Drill a hole in the center of your original focus knob to accept the cable. Epoxy the speedo cable to your original focus knob and epoxy the other end to the larger knob. This worked well on my 125 the larger knob helps a lot in fine focusing. Making the replacement knob as light as possible will produce produce less stress on the focus exit shaft and plastic exit point at the rear of the scope. You may want to "sleeve" the focus shaft but that another mission.
The meade 1244 would be the best solution. I modified one for my etx80 that I bought for $29 a several months ago. A short video of focuser in operation in link below. The wiggle at the start and wiggles at the end are the controller being removed and replaced on the velcro attached to the tripod legs.
Just be mindful of an extender that has a long collar that slips on the focus shaft since that will limit the scope's pointing at zenith or directly upward. Also make sure the cable or tubing is felxible enough to keep it from binding or wiggling about while focusing. Some cable focusers are too stiff and slightly moves the OTA as you focus.