1. Use a 1/2" endmill for motor recess. Cut this area first as factory motor boss is in the way.
2. Verify your unit’s frame measurements against mine.
3. Use Parallel plate under axle base edge of frame in vise.
4. Clamp with a ½ x ½" x 2" piece of keystock along outside of axle/spring boss, with wider portion of frame above vise jaws.
5. Ensure frame wider mid lip is dead straight level. Tap down tightly.
6. The 0.817" depth of the recess is measured from the center of the rear factory motor boss on my unit. This depth barely started removing material from the visible curve of the boiler belly. Both frame halves must be cut equally.
7. If a larger recess depth is required for other motors, use a ball end mill and leave all visual belly material intact – just hollow it.
8. The original assembly screws and spacer must be retained. These will also be used to attach motor wires later.
9. Deburr all cut edges.

1. Use a 3/8" endmill for the gearbox recess.
2. My frame measured 1.195" from axle center to the frame top edge at the recess.
3. Carefully measure and scribe the cut line on the frame top surface. This is very important.
4. Clamp the frame half in the vise by the top surface and the axle boss bottom surface. Be extremely sure that the scribe lines are safely above the vise jaw.
5. Ensure the frame is dead straight level in all directions. Use a dial indicator on a fixture arm in the collet.
6. Cut to the 0.068" depth full frame height. Ensure the width is centered on the axle centerline.
7. Then cut the extra depth area. The cutter radius forces a wider recess area here.
8. Deburr all cut edges.
9. Test fit the gearbox by assembling the frame with all spacers. Basically the recess slot was 0.260" at the bottom and 0.334" at the top on mine.

If all fits, assemble unit after proper lube is applied to all gears, axles, linkage, U-Joints and shafts. Re-glue cylinders to frame and attach valvegear.

Epoxy a styrene piece to the frame side to prevent the gearbox from rotating as the factory frame recess allows too much room.

I mounted the motor with a 0.75" x 0.030" x 0.188" styrene strip under the case ends and RTV in the middle (only) to isolate vibrations. A mount could be fabricated, but the frames must be insulated carefully.

If the axle shafts are needed due to cracking or warping, Use DELRIN and turn 0.368" rods to 0.148" diameter, and bore the ends 0.077" to a depth of 0.15" to press onto the wheel studs. I replaced all four of mine.

I do not recommend it, BUT a good drill press and new cutters might be used to mill the frame. Shallow cuts are required. Only if the quill is very tight and sturdy. The depth of cut will be very difficult to control tho.

If all else fails, contact: