It will not hold the signal as long as it used to.

Is it "Aquiring Signal" or "Antenna Not Detected"? It could be the antenna, the dock, or the radio itself. For whatever reason, the Sportster 5 seems more fragile in the dock connections. TSS Radio has a repair guy who can fix this issue. You can reach him via email at [email protected]

Thats a strange problem. It could just be the dock, but you can get a whole new XpressEZ and car kit for the same price as the dock here:
http://www.tss-radio.com/products/xm-xpressez-receiver-and-car-kit

Could be the antenna, the dock, or the radio itself. If you have another kit or boombox, I would try swapping antennas out and so forth to narrow down which part is causing the issue. www.tss-radio.com has replacement parts.

Hello
If the set receives FM signals without any problem, and only fails to receive AM signals, the IC [integrated circuit] used in it is faulty. The number of the IC used with your radio is CXA 1376AS. It is a replacable type IC, and can be bought from most of the electronic spare part shops at your town. If you want further details about its service manual, get me by Fixya. OK.

Get a new dock if you think its the dock. If that doesn't fix it, then your dock connector has a broken solder joint from years of wear and tear. It's common, and a very easy repair. Just resolder the connector to the board.

Remove the back cover on your radio. The antenna connector is located on the right of the dock connector. Carefully resolder the connections. There are 2 pins (they lead to 3 contacts). Very easy repair, all you need it a fine tip soldering iron and some flux. You can get those for around $15 at wally world.

Check the antenna's connector for your car based antenna. Sometimes the little finger tabs need to be gently pushed back towards the center to make a better connection. Be careful not to move them more than a precision screwdrive blade's width or you might snap it off.

Yes, these radios have the plugs going in and out all the time, and that typically wears them out as they do NOT have a dedicated dock for the Roadys like they do for the SkyFi's etc. Not much you can do other than get it into position where it works and leave it there.

You have probably lost a local repeater. Try moving it temporarily to a south-facing window. Here's another one to try: Put in dock and turn off with button on unit. wait 10 seconds, now press "2" "0" "7" "XM" buttons one at a time in that order ON THE FRONT of your SkyFi2 and the radio will go ON by itself! Now, press "Display" 4 times. You will see a screen that says "SAT1", "SAT2" and "TERR". You need a constant checkmark for DEMOD on at least one of the 3 boxes. Please tell me which ones are checkmarked and the average "BER%" number is. The lower the BER% number, the better. If BERis 100%, you are out of luck. Write back and let me know what you read. Press "Display" 5 more times to go back to regular screen. Thanks,
John

Sirius does not stand behind their products, There is no out of warranty repair for their radios,  and they do not offer sites for repair. Seems  like this is a definite problem with this model. Their solution is to buy a new radio,(with all the new-docking,boombox etc) accessories. also they charge $75.00 to change to the new radio.I liked my sportster 1 because of the FM modulator. It just had to be centrally located and all the radios in my home picked it up(no docking) the new radios require $50.00 docking stations for each stereo location and radio location, unless you bring a boombox everywhere, and the sound isn't the same.    I feel there should be a class action lawsuit against Sirius for these reasons and I might look into it. What do all you think?