Tubes gradually get worse with time.
In a well designed valve system, valves work WELL until they don't.
Does that make sense? As long as they BIAS out, and have no physical problems. They work well until failure or pulled when they get close in a routine maintenance check. If the valve needs to be balanced, and they are. Your good!
The pin treatment thing, is always good. Just BE CAREFUL. Tube base can get hot, no excess, no drips, none of that.
Great stuff though, contact enhancement, gue.. carbon base stuff, very conductive, graphite, graphene, some type of snazzy stuff.
I use Rislone and cotton balls, and plunge the pins several time into the lightly soaked cotton wad, a light wipe, and they work perfect...Be clean don't get oil everywhere. The gue shouldn't be moved right, what happens if a valve gets bumped... weeks to settle back in... The Rislone way, plug and play, they sound good, they sound the same, until the next maint cycle. It's a mechanics way, and a very OLD way...
Regards