replace sidewinder 6000pc brain?

I purchased a very nice '86 VW Scirocco 16V in 2001, with a DEI Sidewinder 6000PC (circa ~1997) already installed. This alarm system worked fine for years - alarm, remote door locks, and starter kill - on one remote. A second remote sold with the car never worked for me, despite installing a fresh battery myself. Over time, the range on the good remote dwindled to a few feet from the car, and then last week, it no longer worked at all, even though the LED on the remote lights up when the button in pressed (fresh battery). I have tried re-syncing with the brain but I can't even get the brain to enter programming mode. I spent considerable time establishing that all related underdash wiring is intact, so I am considering swapping the entire brain out with a new-old-stock unit, complete with remotes. My searches on the forums here seem to indicate that several different DEI systems would plug right in. (Sidewinder, Viper, etc.) Is my understanding correct? Or, do I need to keep with the same model line (Sidewinder, 5000, 6000, 6500, etc.)? Where I could find out a bit more specifically which models are compatible with this harness (or if anyone here can just rattle off some models if they happen to know them) so I can keep my eyes open for a replacement. TIA!

I forgot to mention that the automatic door lock function upon ignition works properly, as well as unlock upon engine shutoff.

When you say you can not get it to go into program mode are you saying that the LED never confirms that you are in program mode or the system just does not respond to the remotes when in program mode? It is possible that the remote just went bad. If you check the date code on the brain of the system I will check the chart to see what remotes are compatible with that system for you.Installer, IT support, and FFL. I need less hobbies.

Update: For less than the cost of a new pair of replacement transmitters, I have purchased a New-Old-Stock Sidewinder 5000 on ebay. Should be here in a day or 2. @ tedmont: Yeah, splicing in connections to a new harness would be easy enough. I was just wondering if I'd be likely to fine a new unit that would plug n play. @ Twelvolts: I think you are probably correct about the remotes going bad, but replacing the whole system with synced remotes for less than the price of replacement remotes alone is my goal to eliminate as many variables as possible. Your offer to look up transmitter compatibility is very kind, please do not feel obligated; however the date stamp is March 1998, and photos of my system brain can be found on my flickr page: http://www.flickr.com/photos/camroncamera/ Additional info: The install manual for the Sidewinder 6000 describes programming as such: 1. Door Open a door. Either the H1/5 green or the H1/7 violet door trigger wire must be connected for the control unit to “see” an open door. 2. Key Turn the ignition on to the run position. The H1/9 yellow switched ignition input must be connected. 3. Choose Within 15 seconds, press and release the momentary button to select the channel you wish to program: Press and Release To Program One time Arm/disarm/panic Two times Channel two output (Silent Mode™/Remote Valet® ) Three times Channel three output Once you have selected the step, press the button once more and hold it. The unit will chirp one, two or three times depending on the channel selected. Do not release the momentary button. 4. Transmit While holding the momentary button, press the button on the transmitter that you would like to control the selected receiver channel. One chirp will confirm that the code has been learned. 5. Release Once the code is learned, the Valet® button can be released. ************ However, I cannot get the system to respond - no chirps, and when I turn the key to "on", the LED flashes 1-2, (pause), 3-4-5. I can't seem to find a lookup for this code of flashes, unless it is considered 5 flashes, which is "Ignition Trigger"... however, the car starts fine with no starter kill issues. ALSO - this car has been constantly plagued by batteries that drain dead after sitting a few days without the car being driven. I thought the alarm system might be contributing to this, (battery drained whether the alarm was armed or not) but have not yet had a chance to isolate this cause. Thanks all!

Second Update: The mailman just delivered the new-old-stock Sidewinder 5000ESP that I picked up CHEAP (~US$17 incl. shipping) on ebay. The main harness plug on the existing system in the car is similar enough to fit the pins on the new brain, but the securing mechanism on the plastic plug is different, so I'm not yet sure if I can get away with just switching out the brain unit without also rewiring the new harness connector. I'll see what I can come up with and provide an update soon. The new unit date of manufacture is Aug. 2001, much newer than I figured it would be (old Sidewinder PC6000HF was March 1998). Thanks

Third Update: Success! As it turns out, my original Sidewinder PC6000HF brain is OK. There were two problem areas with the original wiring. The Valet button had lost a connection some time ago, and my recent solder repair was not a fantastic job, as there was a frayed lead that wasn't properly stripped. Also, the receiver antenna wire had come loose from its connector, causing my severe lack of transmitter range. The new antenna wire connector was not a direct fit, but I have made do temporarily. My main problem, however, was dead remotes. With a new Valet button and new antenna wire, the old system was easily able to enter programming mode, and synced right up to the new remotes. I now have proper arm/disarm with lock/unlock, silent or chirp, and I can do such from a distance, without having to stand right next to the driver's side door. Thanks for everyone's input.