Hi again timothj,
Glad this lead you to getting the mic repaired. I'll repost my
clarification as the official answer.
There is a lot you do not say that I shall have to assume in your
question. I assume you are in the USA and that since you do not
mention warranty, the mic is not new.
Most likely, with an "echo" quality, the problem is in the mic
electronics. There is no way to estimate the cost of repair without
looking at the mic.
This link will take you to all of the reps for Beyer in the Us listed
by state. In general, they are very good folks and will steer you to
both US factory repair as well as any local repair facilities in your
area if they exist. Just select your state and call the rep. I'm sure
they will be helpful.
If this works for you and you consider it a sufficient answer, do let
me know and I'll be happy to post as such. If not, perhaps another
researcher will come by with local knowledge of independent shops if
you let us know where you are located.
Good luck with the repair.