We have some 6 MX5200 stations in use. 4 MX0DS1 de-soldering guns. I have rebuilt many of these MX-DS1. The factory tech support is very poor and not user friendly.
What I have learned is (for me) the best air supply should be set to 70lbs regulated.
With that setting the vacuum should be at lease 17 in.
Replacing the venturi may help.
Also make sure there is a little light grease on the rubber gasket.
If anyone has air leaks, you should not. When working properly I have at least 3 on one regulator for days (valve closed) no leaks still at 70 lbs.
Too much or too little and you won't get the correct suction.
Any forum admins here, please post this where it will get some Metcal users help.