It's been a while since I played TPM, so I'm not sure what part you're talking about. Is there an elevator that stops at the ring you're trying to jump on? If there is, you should wait till it get's to the bottem.
If there isn't an elevator then I'm not sure what part you're talking about, but I could probably load up a game in that area and find out.
*Stormtrooper commander in front of his troop of stormtroopers walks up to general*
Commander: "We have succesfully defeated those two wookie armies."
*An Ewok starts throwing pebbles*