When I got my KLP1 there were some problems by design. One Problem was the lower belt on the right rear side. The idler pulley is mounted too far to the left, resulting in a non-parallel belt path, resulting in different belt tension depending on the current position on the Y axis, making the whole Input-Shaper-Thingy useless for the Y axis.

With this model you can re-position the idler pulley to make the belt path go parallel (at least on the right side - the belts leaving the extruder mount on the right are another story).
This mod does not reduce the usable print volume of the printer as some other mods do.

Needed parts:

• 1x printed "KLP1-Idler-Parallel-Fix" (added a solid option as well if you don't like the voronoi look - but the part is strong enough with the pattern on this side of the idler)
• 1x printed “KLP1-Idler-Top-Support”
• 3x M4 x 16mm screws
• 4x M3 x 8mm screws with washers

Print instructions:

• Material: ABS (Petg might also work - pay attention to heat resistance)
• Layer height 0,2mm or 0,25mm (to reach full 1mm heigths of the parts)
• No Supports needed (load the parts into the slicer as i uploaded them)
• Seam position “left” (maybe rotate the part 90° and set it to “back”)
• 3-4 walls
• 5 top and bottom layers (4 if you use 0.25mm layer height)
• 20% infill

Installation guide:

Prepare the printed parts by installing only the 3 M4x16mm screws first (cleans the threads after printing - go slow when turning in the screws as the thread could melt due to friction - thx Carlo Vaccari for this info)…

… then remove the screws and losely mount the Idler-Top-Support using only the left screw…

… now the parts are prepared for installation. So get to the KLP1:

Step 1: Unplug the Printer after lowering the build plate (or turn the lead screw by hand after unplugging).

Step 2: Remove acrylic panel on the right side to get easier access.

Step 3: Loosen the belts tension using the screws on the back left side of the extruder carriage using a 3mm hex key.

Step 4: Remove the idler pulley using a 2.5mm hex key and remove the timing pulley from the right motor using a 2mm hex key (2 screws must be loosened, no need to put them out completely). Then remove the 4 marked screws using a 2mm hex key (store the 5 screws at the other replacement parts of your KLP1):

Step 5: Insert the lower belt in between the two printed parts and insert the second M4x16mm screw to the right hole:

Step 6: Insert the idler pulley (the belt shoud go around the right side) and fix it using the 3rd M4x16mm screw. The 3 Screws can now be screwed in tight (check if the idler pulley rotates easy). Now check if the belts did get tangled before screwing down the whole bracket using 4 M3x8mm screws incl. washers (marked green). If it is hard to allign the screws you can loosen the orange screw a bit:

Step 7: Place the lower belt back onto its idlers and place the timing pulley back onto the motor with the upper belt back in its path. If the lower belt got too short (maybe loosening your belt tensioner did not give enough length) you can loosen the 2 screws which hold the belt in the tensioner blocks and pull out a few milimeters of belt before tightening the screws in the belt tensioner again (Kingroon made a Video about it - parts are shown at 1 minute and 13 seconds - but don't pull the belt in like in the video: https://youtu.be/KTIaxn7dI8A?t=73).

Don't forget to tighten the 2 screws on the timing pulley and put back some tension to your belts. Check if the extruder moves easy by hand.

Step 8: Start the printer, hit “Configuration > Input Shaper > Auto-calibrate” and let it find the new Input shaper settings.

Step 9: Leave a ⭐⭐⭐⭐⭐ review and add a picture of your fixed belt path 😎

Step X: Report any errors or missing information to me (sry if that happened) 😊

Step XX: Finally have fun using your (now better) KLP1!

(If you have access to punching sheet metal, I will upload a model you can use with 2mm thick metal sheets and link it here in a few days when I get my prototype delivered)