1. Begin by powering off your printer and unplugging it from the wall.
2. Remove the back plate.
3. Remove the hotend assembly by first twisting it clockwise up off the X rod and then to the rear off of the Y rod.
4. Remove the top plate by taking out the eight screws circled in the picture below.
5. Take out the primary feeder assembly (the one on the left as viewing the machine from the front) by unscrewing the screw in the picture below.
6. Remove the wires from the slit in the acrylic above the feeder assembly screw.
7. Cut the zip ties holding the wires to the inside of the acrylic.
8. Being very careful not to cut the wires, cut the heat shrink off of the ends of the woven cable sleeve. Insert one of the blades of a pair of scissors into the wire end of the heat shrink and split the heat shrink open lengthwise bit by bit. When you get to where the heat shrink meets the woven material, make sure you get the blade of the scissors between the heat shrink and the woven sleeve. Do not cut the woven material.
9. Remove both of your belts that are strung left/right. To do this, unscrew the screw from your front and rear belt brackets. The hex nut is face up, but the screw can be accessed beneath.
10. With your allen wrench from underneath, loosen the set screw that holds the belt pulley to the rod underneath the front left corner bracket. Do not remove the set screw completely. These are tiny and easy to lose.
11. Slide this rod out towards the front of the machine until it protrudes about an inch through the front acrylic plate.
12. Remove the screw that secures the rear left corner bracket into the acrylic side plate as show in the picture below. Try to keep the hex nut within the corner bracket.
13. The picture below shows the top two screws of the X axis minimum limit switch mounting bracket. There are four screws in this piece. Completely remove all four. Keep the hex nuts in the inset spaces they occupy in the rear left corner bracket.
14. Twist the rear left corner bracket out. Remove the 3d printed and acrylic pieces between the motor and the inside of the rear left corner bracket. Take off the rear left corner bracket. If you move the limit switch mounted in the rear left corner bracket to give yourself some extra room, you'll have to remember to put the limit switch back to it's original position when reassembling later. Take a picture for reference before moving it if you decide it's necessary.
15. Loosen the screw that holds the Y axis motor to the coupler that connects it to the rod. Do not remove it completely. These screws are tiny and easy to lose.
16. Gripping the motor connector rather than pulling on the wires, unplug the Y axis motor from the Rambo main board. Pull the Y axis motor wires out of the woven sleeve.
---Installing the new motor---
17. Push the Y axis motor connector into the woven sleeve. At some point it will become difficult to push the connector through the woven sleeve. When this occurs, pinch the connector through the sleeve and bunch the sleeve beyond the connector up towards the connector. With the fingers you're drawing the sleeve up toward the connector, pinch the connector allowing the bunched material to un-bunch along the length of the motor wires. Use this scrunching method to thread the motor wires all the way through.
18. Disconnect the white and black limit switch wires/connectors from the Rambo main board and pass them through both heat shrink tubings. Unclip the red and black wires/connector from the Rambo main board. Unscrew the little flathead screws that join the ends of the black/red wires to the connector block and pull the wires out. Pass them through both heat shrink tubings as well. Pass the four color Y axis motor wires through both heat shrink tubings as well. Slide the heatshink tubings down and position one at each end of the woven sleeve. Use a heat gun or a lighter to briefly apply heat to the heat shrink tubings. If using a lighter, keep the very tip of the flame near the heat shrink tubing. Pass the lighter quickly under the heat shrink tubing. Do not hold the lighter stationary or engulf the heat shrink tubing within the flame. Do not hold the lighter upside down. Do 4-5 quick passes to completely shrink the heat shrink tubing.
19. Reconnect the limit switch, red/black wires, and motor wires to the Rambo main board.
20. Couple the motor shaft to the rod pictured in step 15 and tighten the set screw.
21. Replace the pieces and corner bracket in step 14.
22. Put the screws back in from steps 12 and 13.
23. Slide the rod back into place from step 11. Make sure the bearing sits in the inset place it's supposed to within the rear left corner bracket. Tighten back down the belt pulley set screw.
24. Put the wires back into the acrylic slit from step 6.
25. Replace the feeder assembly screw from step 5.
26. Restring both of your belts removed in step 9. The second screw beneath the bracket pieces can be tightened to tighten the belts.
27. Replace the top acrylic plate removed in step 4.
28. Put the hotend assembly back onto the X and Y rods.
29. Put the back acrylic panel back onto the machine.