This is sort of what I'm thinking since there was TONS of lube build up before the dealer changed the cog.
But what could be causing the link?
As mentioned above there are two types of fluid that can leak from that area, DOT 4 and engine oil. You can generally tell the difference just by feel and smell (and maybe an accidental taste).
If it is DOT 4 then you know the slave cylinder is the culprit and needs to be rebuilt or replaced. I replaced mine instead of rebuilding.
If it is engine oil then click on the link in my post above and you will see information on how to replace the two seals that would be the culprit. You will need to access both the seals to replace either one so I chose to replaced both while I was in there, however, more so that I wasn't sure which one was leaking. After removing the seal retainer and seeing the amount oil behind the retainer at the counter-shaft seal I think that was the culprit.
2012 DL1000 Adventure (Tinkerbell)
PC-V, TRE, CR8EIX , ECM, K&N, RDL, PR4, PC-8, EB H4, WERKS, Madstad 22", 17/43 gearing, AdventureTech: Fork brace, shelf, mirror extenders, SpeedoDRD, wheel spacer, Head's-Up voltage monitor, Goldwing pegs, Sonic 1.1, Wolo Bad Boy, ExTuff Helmet Hook.