Too many jets not enough flow and wide brush that's my tuppence worth
No, that's the same as mine, its fine. Just hold brush nearer glass when rinsing.
Might be worth trying 100's. I use them all the time having started out with 50s. I think they might be a finer bore than the 50s so possibly might work better in fours? I prefer them. I like the way they fill the full width of the brush and the lively fizzing sound they make. Impresses the customers as well when they can not only see but also hear work being done. I do only ever use two and I only use standard width brushes, so no personal experience of four up.
We do t generally use brushes with 4 jets and when we do we don’t use fan jets , I seam to recall @Alex Gardiner saying that with some brushes you need to cut some bristles off to get the fan jets to spray properly
You do need to trim slightly for some brushes to properly suit fans. I've never needed to for the ones I use. The trim would required should be minimal and easy to identify. Watch which bristles the water is hitting and trim to suit. A vee shape trim opening out from each jet will do it. Taking care to only trim what's needed.
