Re-waterproofing a tent fly

My trusty old NF Tadpole just started leaking like a sieve. The fly LOOKS great. No holes or visibile wear through. But obviously the coating must have undergone some sort of horrible transformation.

What's the best way to refresh the coating on the fly? Or do I just give up on my old tent?

I used Aquaseal Poly Coat on the inside of the fly and floor of a 30 year old tent.  I also sprayed some type of water repellent coating on the outside of the non beathable parts.  Totally waterproof after that. 

It look like aquaseal is out of orders everywhere, is there something else that does it??

Time for a new tent

Going to give it a try with some silicone spray they sold me at the local adventure store. 

Goulet Goulet wrote: It look like aquaseal is out of orders everywhere, is there something else that does it??

Get a lifetime supply here!

http://www.bestmaterials.com/detail.aspx?ID=11185

I've successfully fixed this problem with three tents over the years. First thing is to attend to the seams. The seam tape is usually peeling, but has almost certainly lost its effectivness even if not visibly peeling. Pull it off if it's loose, scrub the seam with isopropyl alcohol, and use seam sealer on them. When that's all dry, insure that the inside surface of the fly is clean (alcohol again if needed), and treat it (the inside, not outside, surface) with 303 Fabric Guard. Be certain to get the Fabric Guard; 303 makes several products and they aren't all suitable. There are other brands of waterproofing but I've been less impressed with them. Nikwax isn't bad, but 303 Fabric Guard is the only one I've found that approaches the effectiveness of the original factory coating.

TNF will sell you a pro rated fly if you call their customer service.  

Thanks for all the above advice so far!