Can I ask are you using a van mount or backpack/trolley and are you scrubbing and washing down the frames too not just the glass?
I was going to say are you checking them straight away after they dry or not. If not then one cause to get spotting and drip marks as mentioned is dirty water running down from the gutter line etc when it rains.
I’ve found the following what will cause spotting & drip marks when cleaning top openers and frames as follows:
1. Top frames not scrubbed & wash down properly to remove all dirt & oxidation
2. Top window vents getting wet inside and dripping dirty water onto the glass.
3. Rubber seals still leaching trapped old soap/dirt or seal bleed from the rubber itself
4. Water getting inside the frames themselves leaching dirty water out of the frame drainage holes.
If you’re on about spotting at the sides or the bottom of the glass again it's down technique as not scrubbing & rinsing down properly. The type of flow, brush, jets you use also plays a part too as some glass sheets so is easier to rinse down properly than the ones that run down in ribbons.
Once I had master wfp technique I soon found out on first cleans with filthy frames and glass just using pure water alone on a low flow rate took ages as needed at least 2 cleans whilst I was there to get them spot & drip mark free. That's when I decided to start using a high flow rate, fan jets, warm/hot water and a boost and now use vision x which has made first clean so much easier and quicker to do. Also makes regular cleans a breeze too.
Vision has feck all to do with it.
In fact if it was me I'd stop using the Vision and expect better results.
I never said it did now did I…
But just so happens warm/hot pure water and visions x for me works out quicker to clean filthy windows and frames properly and on regular cleans too which also dries out spot free and run marks free all the same. That is if you have mastered the basic wfp technique in the first place.
There are other chems you can spray onto a wfp brush that will also help with rubber bleed and oxidation of frames.
If you are unsure of the problem just do a wet finger test and rub yer finger along the frame for oxidation or for rubber bleed rub yer wet finger along the rubber seal. Your finger will either turn white from the frames or black off the seals or remain clean.
It goes without saying any dirty water left dripping down from the surface above be it lead flashing, cladding, tiles, brickwork, stone/concrete lintels, fascias etc can affect the results of a window clean.
