aww dang, I thought I had "before" pics but can't find now... oh well here's the "after" pic. I think the colors are pretty much exactly the same as before, including lighter top and darker crease-marks; I think it was garaged top-down for months at a time by PO, perhaps that somehow created the slight crease-mark patterns.
Ok on second look, the top is still the same color but more uniform, maybe a bit brighter if that makes sense, and definitely has some visual "pop" compared to before.
I used Griot's Garage convertible top cleaner and convertible top protectant.
On a sap stain, I tried some 3M Adhesive Remover that Griot's sells in their flagship store, as recommended by one of their senior guys when I asked him to come out and take a look at it. I liked it better before the 3M application, but worried the sap compound could eventually degrade the fabric. Again, I forgot I did not have a "before" pic, but the sap-stain pattern was distinct line of lighter-colored drips, apparently the best the PO's detailing shop could do on the detailing level she bought. Now the light-colored look is gone, the drips are smaller, but there's a watermark-type line at the perimeter of the work area (about 1/2" out from the drip, all the way around). This was the extent of the 3M solvent's wicking action. Rather than spray it on, I sprayed it on a tooth brush, then carefully worked just the dots of sap; on a dry top that probably hasn't seen a solid coat of protectant in 8 years, it wicked out fast. I cut short the effort to prevent further wicking, as I worried I'd get exactly this kind of work-stain from it.
The close-up may make it look pretty bad, but it's present in the above photo too - and about that hard to spot when your passenger is walking around or entering the car.
We washed immediately after stain removal, using 9 oz in one wash. Wet-down included a good soaking, then some low-pressure fan spray to loosen up dirt without blasting the top. Sprayed cleaner, gently worked up lather with horsehair brush in sections about 2 sq ft at a time; then another gently pass with brush over the whole top after lather had time to loosen any last bits. Hosed off with gentle spray until mostly clear, then a more aggressive low-pressure fan spray til water ran completely clear. Parked it under awning to dry overnight. (sorry no pics during washing)
This being our first treatment we really drenched the top, using 28 oz total in 2 coats. I masked with 6 mil plastic sheet we had left over from another project. I should have gotten some 0.7 mil plastic instead: much cheaper, won't pull up the painter's tape you tack it down with, easier to work around the corners at rear hinge points. I pulled off the masking as soon as 2nd coat had set up (about 15 minutes) and glad I did: protectant had pooled at the hinge corners and dripped down the side of the car, despite my efforts to keep dabbing up the pooling liquid. It also got under the tape on the rear window bottom.
Even after sitting on the paint for maybe an hour in some spots, it seemed to clean up pretty easy with a good wipe and some Quick Detailer spray (a light-blue dilute cleaner + wax Griot's product) just to be sure it was off without leaving a gap in last week's light-wax job. Next time I'll use the right plastic, a more-complete skirt, and mask those corners in a way that allows a clear path to drip off. I'll also double-tape the window's bottom edge (tape then plastic then tape), so protectant can't run under the tape.
I left it parked for a day and a half to dry and cure. Drove it in a steady light-to-medium rain on the highway for a couple hours last night; after a half hour it was still beading up on the newly treated top, where before it had all the water resistance of an 8yo Turkish towel. What really surprised me was arriving home and finding it was still beading up! I doubt this will last, and all products warn that a heavy rain will eventually soak through, but I am pleasantly surprised with the effectiveness of the cleaning and treatment.
