[TR] TR6 Clutch Hydraulics

[George Haynes]

Listers,
A friend has a 1970 TR6 in which the clutch pedal requires an excessive amount
of force to disengage the clutch.  Considerably more force than other TR6's I
have driven and more than my TR4A.  We installed a new, stock pressure plate
last winter.

Could hydraulics be a fault?  The early 1970 took a Master cylinder bore of
.75", while later 1970's and newer took a .70" bore.  Slave cylinder diameters
are apparently all the same.
Assuming he has an early car, would his problem be improved with use of a
later, smaller bore MC?

It's not fun driving his car.  Could something be binding mechanically?  The
slave pushrod is in the center hole.
Thanks for any insight and advice.
George Haynes