My Ultimaker 2+ started jamming a ton and I discovered that the extruder lever had warped at the bearing mounting point causing it to bind. Using the UM open source files I modded the lever arm to assemble with screws - making everything much stronger. I used ABS with higher infill. Use M3 x 10 flat screws or #4 x 3/8". Prints without supports. This should work for the 2, 2+, 3 - not sure about the S5.