Troy-Built Model 0203400 no pressure. Tried all suggested remedies and even opened unloader valve and put back. Can't tell if unloader value is broken or not. Trying not to replace the shoe pump.

SOURCE: replace pullcord on troy built mower

Replacing the rope is not difficult but tricky. I believe that your model has a fuel tank on top of starter cover, empty fuel and remove tank to expose starter cover. Remove the starter cover and place it on your workbench with the plastic rewind spool visible and remove the old rope noting how it was tied. The rope is sold in various sizes from # 3 to # 6.5. Most mowers use a #4.5, with length of about 6 to 7 feet. You may not need this much but more is better. Now practice inserting the rope thru the hole where it comes out of the cover into the hole where it ties on the spool. Once you can do this you are ready to wind. The spool /spring winds when you pull the rope, that why it recoils when you let go of the rope. With that in mind, turn (wind) the spool in the same direction that it turns when you pull the rope. It should be getting tighter as you turn. Keep winding in the direction that it turns when you pull the rope untill it will not go anymore. It should be very tight. Now unwind one complete turn and align the hole of the spool to the hole in the housing and hold it there while you insert the rope from outside hole into the spool and tie knot. After the knot is tied slowly let rope rewind into the spool untill it stops on its own. You are done. You should have plenty of extra rope left to extend out to the handlebar. Enjoy

SOURCE: How do you clean the unloader valve on a power washer pump?

The unloader valve usually is replaced. I dont know if you can get o-rings for it. But if you want to take it apart, there will be a crown or cap style nut just below the spring. Unscrew it completely and you will be able to remove the spool. There is just a series of o-rings on it.

SOURCE: Karcher K 2400 HH Pressure Washer no pressure

http://www.landanorthwest.com/documents/instructional/spill_valve_instructions.pdf

SOURCE: Karcher G3050OH Pressure Washer Spill / Unloader Valve (Bypass)

You should put 'locktite' on the male thread and screw it in all the way and lock it there. That is how it works ,the spring keeps the valve at the bottom closed during high pressure operation. When the gun is released the part with the o-ring is forced down resulting in the valve opening and then the pressure is by-passed.Those dont normally give trouble. Look for a blocked nozzle or a restriction somewhere in your high pressure hose.

SOURCE: Unloader Valve - Karcher Pressure Washer

where is the unloader valve locaed on a Briggs Stratton pressure washer?