If you're guides are good, no need for a sleeve .
Need for tightness to kill all vibration varies.
Setups with a lot of preload, like you ususally find in the Supersport/Lightning often need tighter guides than other guns,
as the preload opens the spring ID when the gun is assembled.
As you say, tight guides often gets most of the lubricant scraped off.
If there is no visible heavy wear marks on your spring/guide, I'd leave it alone, or perhaps smear some high content moly grease between the coils.
Too many airguns!
I sympathise as I have seen a couple of rifles with this symptom. As noted, it can be due to the cocking link or shoe riding over the coils but if there is a sleeve in place then this is not so. But I have also seen a case where the spring itself was slightly too big (too large diameter) such that there was little clearance between spring and sleeve, or sometimes caused by sleeve being too thick (I have seen this with PTFE or other plastic sleeves but it can happen with much thinner steel sleeves) such that on cocking, the spring catches on the sleeve as it compresses; the sensation transmitting through the cocking action. I note the action had been 'tuned'. Maybe an aftermarket spring with a greater od than original .. fraction of a mm could do it. Or too thick a sleeve. Might be worth a check. If the spring is a quite firm sliding fit in the sleeve then maybe sleeve is too thick or another spring is needed.
Cheers, Phil
I've seen two different sleeve thicknesses on the Supersport/lightning, so you may have the option of fitting a thinner sleeve if that turns out to be the problem.
One thing with the cocking lever is that it is not properly profiled from the factory, which means it digs a track in the sleeve.
Easily remedied with some dremel work to the lever, just make sure you done take off too much, just enough to clear the sleeve.
Too many airguns!