Karcher pressure washer (Nether Edge S7)

Probably 10 years old. Worked brilliantly first year, but when tried the following year, kept losing pressure. Been in cellar ever since, and not able to test because of hose-pipe ban. Seems pity to take it to tip if someone can sort it out, or even use it without lot of pressure. I used it first year to pressure -wash the patio.