Greenworks Pressure Washer Plug Repair

I've got an 3000 PSI electric pressure washer by Greenworks I picked up from Costco...I've had it a couple of years and and it always worked great for what I need. At the end of last summer I needed to clean a part of a deck around a pool that it wouldn't quite reach so I used an extension cord to give me a few extra feet to get the job done. Fast forward to this summer and when I started to use it I couldn't unplug the extension cord. I started to use it and the built in-line GFCI installed to the pressure washer cord trips after a minute or two. It seems like that short extension cord was too light weight and the power that the washer drew through the extension cord welded the extension cord to the pressure washer cord. Since I can't unplu the extension cord I assume that to fix this I should cut the cord at the end of the plug for the pressure washer and replace it. Just trying to get a reality check that this will fix the problem and get a suggestion on what specs for the new plug might be....don't want to install something that not rated for the power the pressure needs to draw.