I doubt if there is any adjustment, I just dismantled mine for similar reason, they contain 'cartridges' with a Viscous fluid, and some of the fluid had leaked out leaving air which is easily compressed. You may be able to get spare 'cartridges' ( but I haven't found anywhere that sells them)
Kevin
November 2010
I can answer this question...
how do I adjust my soft close hinges, the lid bangs down now?
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