Stem question

Good evening, I started pipe smoking about 3 years ago and bought a couple pipes and some tins of things and really enjoyed it for the short time I was able to do it. Life got in the way and I've recently had the chance to pick it back up again. The only problem is, between then and now one of my pipe stems turned really bitter and I can't smoke out of it. First, is there a way to fix the stem so it isn't bitter? Second, if not is there a way to get a replacement stem so that I can continue to use the pipe? Any help would be much appreciated.

http://imgur.com/a/w1G1t Is a picture of the pipe in question. Its a Wessex Standard