I had a similar problem with my XM reception and after a lot of trouble shooting decided to call Garmin.
They sent me a new XM antenna free of charge after I mailed them the old one.
I too was not the original owner of the Garmin 696.
The reception problem was immediately resolved with the new antenna.
Call them, you will be pleasantly surprised.
http://www.vansairforce.com/communit...ight=reception