The unit uses a peristaltic pump, with two motor driven rollers alternately squeezing the hose and pushing material forward. You will need a #288623 replacement pump hose. This is for an RTX2000pi. The 1400 pi and 2500pi are very similar.
* Turn off the sprayer and wait 7 seconds for power to dissipate
* Unplug the sprayer
* Back off the material feed control to minimum so the tension on the hose is less.
* Relieve the air pressure in the air hose with the priming valve.
* Disconnect all the hoses from the front of the unit.
* Remove the material hopper.
* Remove the pump access door on the left side of the unit. It's the side opposite the switch side
** You will need a 3/8" nut driver to undo the bolt.
** You can rotate it up out of the way and then tighten the knob that also holds the plate so it stays up
* Remove the knob right next to the place where the hopper connects to the inlet port . This holds on the hose plate.
* Lift off the hose plate.
* You can slide the pump hose to the left
* Squeeze the pump hose together and remove it from the unit.
* Install the new hose (the clear part toward the rollers).
* Slide it to the right so the grooves on the hose couplings are held by the front plate of the unit.
* Replace the hose plate and reassemble the remainder of the unit in reverse order.
Here's a link to a [link|https://www.youtube.com/watch?v=Xi_vBARzbAs|video from Graco|new_window=true] of the whole process.