I use a Karcher and had the same issue some years ago. I now always drain wand and run motor 'dry' before putting it away.
If you can isolate the leaking issue there are often spare parts available on ebay but if it was a cheapy, why bother?
Karcher do graded washers on their own site occasionally, and lots swear by Lidl own brand but they only are stocked once or twice a year..
I bought a NOS 3 series karcher on ebay new for around £75