Powercraft pressure washer?

Its a few years old and not the current model.
When you first start the unit you have to remove the nozzle.then its powers up. You then replace the nozzle and it then works. But you have to go through the same proceedure every time you take your hand off the lever. its no great problem and its done it for years but I would really like to fix it. Does anyone have any ideas please ?