hoover six etc poor fill.

had this a couple of months ago,hope it helps anyone. customer complained of m/c not filling with enough water, hence poor washes 🙁 . did the usual pressure chamber/ hose checks, then i pulled the small hose off the back of the dispencer which connects to the tub & ta da! it started to fill to the correct level. turned out due to the cacky water we have in these parts had clogged up the dispencer top, had to replace it ,but everything is fine,for now till the next time. anybody know how to stop this dark gooey stuff gathering in the dispencers apart from removing em’ & soaking em’ in water & bleach? 😡 ?
take it easy out there guys n’ gals. 8)