As for mine, I figure is my Sunbrella is leaking like a sieve, machine washing it is not going harm anything since the original coatings are all gone. I once did hand wash and coat it with 303, that didn't last long or did much good. I reckon there're still alot of dirt on the fabric. When I machine wash it (front loader) I find lots of speckles of black dirt came off with the washed water. Thereafter, recoating with the repellent really works great.
2002 Hunter 326, SV Millennium 2
1999 Macgregor 26X, SV Millennium