Strange Clutch Problem

Hi Guys, Wondering of anyone can enlighten me on a clutch problem I'm
encountering with my 59' Lark.  It has the 6 cylinder engine with a 3
speed (no OD).  I noticed that the point of engagement for the cluth
was becoming lower and lower (to the floorboard), so I adjusted the
released rod on the linkage as the shop manual instructs.  That
adjustment eld fine for a couple of weeks, during which the point of
engagement once again, became lower and lower to the floorboard.  I
once again adjusted it, however this time, it sank back down to the
previous low level with  about 10 applications of the clutch!  Rather
than keep adjusting it further and further, I am wondering what could
be causing the clutch to keep going lower and lower simply by applying
the clutch pedal?  I'm not 100% certain on the precise mechanics of
how the clutch on my Lark operates, other than I know the pressure
plate is pulled back away from the driven plate to make or break the
engagement.  Is it probable that the pedal linkage is worn down and
requires attention, or is there something within the internal clutch
itself that would cause this condition?

Any thoughts or suggestions?

Thanks,
-George-
-59 Lark Regal
-63 GT Hawk
-63 Champ Pickup