I bought one of these inexpensive Sun Joe SPX1500 for less than $100 new in 2019. I've used the heck out of it from power washing the house to retaining walls to decks to walkways to fencing and even to farm tractors and it's still going strong. A little less GPM than yours but I'm on a well so gotta be careful. They do make bigger units. For less than $100 and 5 years of good use it's a heckuvalot cheaper than buying parts to try and keep an older one working IMHO. I got mine at Lowes.
https://www.amazon.com/Sun-Joe-SPX15...01IJ2SCF0?th=1