The slide on the far left looks good, it is not. Very stretchy, gonna hole as soon as it gets hit with a few strong vacuum pulses.
Random thoughts and rambling, feel free to add your experiences.
- I don't hold a strong opinion about adding seafoam etc to the tank. I suspect it is not a great idea but can not say with authority it is bad either.
- Another method is forcing cleaner up thru the drain nipple with a syringe and letting it soak. Drain and flush with fuel and I'd call that safe and as effective as anything else you can try with no risk to the diaps. Rubber bits like float needle tips and fuel tube seals?

- Heavy dose of seafoam thru the tank? I see 3 outcomes.
1 - Assuming the idle circuits are not completely plugged the cleaner can flow and clears them. Vroom! Yay!!
2 - The cleaner loosens the sludge in the tank, hoses and carbs and plug the idle passages solid.
3 - The idle circuits are plugged solid, the cleaner is unable to flow and you wasted a $5 can of seafoam.