I think hydramaster sell jet screens/check valves etc. Check valves will stop your jets dribbling when the trigger isn't pulled but in my experiences the springs don't last very long. The screens are an essential piece of kit. If you've got bog standard brass jets, you can buy a new set of stainless with the screens and/or check valves and enjoy months of trouble-free wanding. Can't remember the last time I even took mine off to inspect and never get blocked jets. cost a few quid but what price do you put on removing a big pain in the a$$?
De-scaling is simple. Turn off supply pump, half empty your header tank, add appropriate amount of de-scaler and circulate through all your lengths of hose, finishing with an open-ended hose feeding back into the header tank. Get her nice and hot, circulating the de-scaler for 10 minutes or so, and also put each wand/tool in line and pump a bit through it. Switch off and let it sit for a couple of hours, then run it up hot re-circulating again for 5-10 mins. Point your open ended hose down the sewer, switch the supply pump back on and flush the system out, including the wands/tools.
Whilst doing this I'd take off all jets from wands and soak in a cupful of strong de-scaler solution. There might be a filter on your supply pump which needs checking for debris.
Good opportunity also to re-charge your water softener, vacuum all the crud out of your header tank, completely empty the water tank and vac the crud out of it too. Then start fresh with a tank full of nice soft water with no bits in it, and a scale-free machine
