I use both a weller wrs1002x, and a pace MBT 201-SD
They both use collection tubes, the weller uses a cardboard replaceable tube, while the pace uses a reusable glass tube.
Basically what happens is the solder get's sucked in, and on the pace it's supposed to hit the little metal insert, cool and stick. No such thing on the Weller. But it doesn't do that so well. Little pieces of the solder still find their way back down to the nozzle, because, you point it that way to desolder.
What I do that helps is try to desolder with the board on it's side that way the wand is horizontal and not vertical. I also tend to put down my wand so that the tip is pointed up, this helps the hot solder stay at the bottom, and not pool up at the collection nozzle.
But overall, you have to clean them out pretty frequent. I can go a full day of re-work without much problem on either, but I will clean them out at the end of the day. On my weller, I have spare collection tubes, and will just swap them out. I then clean them all out at once. I know they are disposable, but I'm cheap..
You will always need to use a nozzle cleaner to keep things flowing, but not as much if you do the previous stuff. Another thing that helps is always having a good nozzle. If the one you are using starts to pit, or get's corroded from use replace it. Also try a nozzle with a bit bigger inside diameter.
This should keep you sucking a little while longer
