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How much play is normal before you replace the top cap? If you leave it a while, does it damage any other components?
Several bushes in the system and keys too so the play maybe from one or a combination of several items, as with most wear depends on use, maintenance and soil type 😉
Had it apart for a clean not so long ago. Pleased with how clean it was inside with no obvious signs of wear. Just seems to wobble fore and aft a lot.
A fore/aft wobble will be either the top cap, the seal head or both...
My reverb (now retired as I've gone with ks lev for the new bike) had lots of play which was mostly cured by replacing the seal head bush which comes as part of the £7 seal kit... Never got round to replacing the top cap at £40. As far as I can work out, play in the bushes will not affect the sealing of either the air spring or the hydraulic systems. Dirt however will get under the seals and cause issues.
@ £7, the seal kit has to be worth a punt first. Cheers.