Any American Standard Luxor toilet experts?

Our new (to us) has American Standard Luxor toilets (probably AS2003.036 non-Vent-A-Way). So far, so good, but last night the flush valve (probably AS47049-0700) cocked up with the plastic pipe staying vertical, and requires a nudge to drop back down). I'll investigate cleaning up the pivot at the bottom, perhaps putting a bit of some sort of waterproof grease on it. However, is there anyone here who can explain the ins and outs of the overall mechanism to me? I actually paid for access to the "theanswerline" toilet site and downloaded the parts lists -- are there any other online resources explaining these obsolete toilets?
Thanks in advance for any help.
Northe (Green Valley, AZ)
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