Cleaning dirty poly fibre cloth

[N2709P]

The wingtip bows are wood.
N2709P

[York614]

Ahh. Didn’t know that. That changes things.

[rsrguy3]

Imrons claim to fame is its hardness, it was very tough, but not flexible, and definitely not something you'd want to use on an stc'd cover system.
Stuart's just sux.... period. The technique required to get a good finish is positively mental, and you'll need to be committed if your working towards a run and sag free finish... if your worried about chemicals, pay someone to do it for you.
Aero Thane is the way to go, it was reformulated from the ground up in the early 2000's with flexibility as the main characteristic, it shoots like butter and if you wet sand between the first and second coats it looks amazing. Superflight and airtech are the only other urethanes id consider, ranthane likes to run like an untrained dog.

Dawn is a fantastic cleaner if you can use hot hot water... the challenge comes with the varnish, if it isn't a quality varnish job you've just soaked your wood with water.... no bueno.

Strip it. Sand it. Use a two part varnish. Recover it with polyfiber, it's probably the most reasonably priced system out there and performs right up there after all these years.

If budget is elastic, cover with oratex and shoot a top coat of aerothane.

Good luck.