:x punctured by rear Verdestein Fortezza TriComp Pro tubular tyre. I am guessing that being vulcanised, there's no manual internal repair possible?
The hole is very tiny and I do have a 100mL can of Michelin Stop&Go but never used such a product. Is it tubular compatible (latex inners) and do I dump the whole can in the one tyre via the valve?
Anyone with practical experience? Will this foam sealant be long lasting?
Vulcanisation has nothing to do with repairability. These tubulars can be repaired, I have a repaired one as my spare. Repairing tubulars is easy enough but many people can't be bothered. It is very difficult to repair a tubular that has had a 'sealant' put into it though, so it is either/or.
The process for repair
1. Find the hole (note that air will often leak from the tube and move around inside the carcass to come out at around the base of the valve, don't get fooled)
2. Detatch a small section of backing tape from the tyre carcass at the site of the puncture. (a bigger section creates more work to glue it back later)
3. Cut the stitches holding the carcass together at the site of the puncture, 5cm should be enough.
4. Pull the fine material (silk?) aside to expose the tube
5. Pull a loop of tube out, patch the tube
6. Stuff the tube back in
7. Replace the fine material a best you can
8. Sew the carcass back together
9. Pressure test
10. Glue the backing tape back down.
It is a small hassle but it saves a good tyre. Sealants have their own issues they are ok when they work but if they don't you might as well bin the tyre. If you let the tyre go completely flat there is a chance that sealant will glue the tube to itself which then tears itself apart when you pump it up again.
I prefer repairing tyres, YMMV.