- The filter is sopping wet and a bit darker when I remove it
- It's tricky but not impossible to get the pipe cleaner down the stem with the filter in
Yes, the filter it's doing its work. Rinse it with lukewarm tap water and set out to dry. Insert another filter whilst the first one dries. You can wash them up to a certain number of times (~10) but they'll just continue to darken. Toss it when it's quite dark brown.
RE: cleaners: you shouldn't have to insert a cleaner mid-smoke to 'soak up the moisture', for that's what the filter is for; besides when your pipe is assembled you won't be able to pass a cleaner to the chamber anyway (see below). For cleaning, however, you do have to take the pipe apart. Please do this when it's cool (let it cool for about an hour before disassembly). You have to do this to wash the filter anyway, so it's no big deal as long as you're careful when detaching the stem so that you don't break either tenon or mortise.
Here's the breakdown on the piping of Brigham pipes (pun intended):
See how there must be a receptacle for the metal head of the maple distillator?
You can think of Brigham pipes as having two draught holes: the Thin Hole, which runs from the chamber to a larger channel (the Thick Hole) which in turn runs to the mortise.
As you can see, in a bent pipe there's no way to pass a cleaner to the chamber when the filter is inserted, but you can do so without problems when the stummel is detached from the stem and you can see down the draught hole. With straight pipes you don't have that issue.
Also, do note that Brigham doesn't drill the Thin Hole dead centre of the mortise, but rather essentially flush with the top of the Thick Hole, much to the dismay of some "purists" who insist that anything not dead centre is "bad" drilling. Your pipe is not drilled badly—this is all by design, and it's a must with the bent versions because of the need to provide a receptacle for the straight filter's head.
Whew! Looks like I posted a lot, but I hope that helps.