hey all, I bought this Chinese double din Zafira stereo a few months back and its been brilliant until the last month,

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all of a sudden the Sat nav is very intermittent it sometimes takes 30+ minutes to connect and then not at all. The other day it was pouring of rain all day and had no signal, todays suns out and its working but weak signal.

Is this a fault with the antenna (screws into the back and fed up so it sits on my dash with clear view of sky), or something else?. I read somewhere that some of them have batteries inside and it may be dead. mine has two magnetic pieces of metal on the bottom under the sticker.. :/

any help advice or point to a better GPS antenna, ive been looking, but I wont know if im buying the same as I have and if it will cure the issue.