Welcome to the forum. Although you can post in any forum, the USA forum is here in case of local regs or laws
Before going down this route, I suggest that you isolate the supply to the WM connectors, e.g. at the stopcock. There's always a small risk when applying 'leverage' and it's prudent to think ahead...You need leverage, adjustable spanner.. mole grips.. try turning in both directions.
Reply to the thread, titled "Washing machine valve" which is posted in UK Plumbers Forums on Electricians Forums.
We recommend City Plumbing Supplies, BES, and Plumbing Superstore for all plumbing supplies.