TIS (traffic information service)

We have had TIS in three of the planes in our partnership for a while
now. I consider it a safety of flight issue. When it is working the
number of unseen planes around you it displays is amazing. I really
don't want to fly without it at this point. Unfortunately is seems
that the data is not being sent more then 25% of the time, if that, in
the Seattle area. I'm aware of the issues of reception, and it's not
an equipment issue with three identical systems (GNS 430/GTX330) having
the same problems. I have spoken with the Center manager and he says
that if the radar is working, mode S and TIS data are working. I am
beginning to think that this is not true. Are you seeing the same
poor TIS data broadcast in your area? Does anyone have additional
information on the issue? I have spoken to AOPA and they are looking
into it. I've spoken with the avionics shop and they hear similar
complaints from other pilots. I've spoken with Garmin and they say
sales of the GTX 330 have fallen to nothing compared with what they had
been. There is no plan to replace our ASR 9 for a decade or so. We
should be able to count on TIS information being available in the
Seattle area for a long time to come. I'd like to see it working
reliably...

Thanks for the help,
Dave