I've used the teabag with a BE112, 4075 and 501. I do all the same way.
1) I gauge the depth between the top edge of the cart and the bottom of the cart.
2) I cut the teabag in a strip thats about an 1/8" of an longer that what I measured.
3) I roll the strip loosely, you simply have to experiment to get what loose is, untill I have a roll just smaller than the inside dia. of the cart.
4) Insert the roll with a slight screwing motion so it seats all the way down and stays in a roll.
5) With trusty paperclip 'pick' inserted in the center of the roll I then unwind/loosen the roll inside the cart.
6) Cut the excess off. Leave this approx. 1/16" longer than the cart. As it absorbs juice it will swell, compress and form a perfect dimple that remains in contact in with the bridge.
Having said all that I switched to papertowels 2 days ago and as well as the teabags worked the papertowels seem to work better still. Set it up the same way as described above. Again, I've used this in the models I mentioned earlier with great success.
Sorry no pic's, my problem, I'm just not patient enough
Good luck!