pronova

hey all , having problem with the turbo 400 in my 69 camaro, when its cold it seams to work ok, when warm it wont shift out of 1st gear unless im on the gas hard, even trying manually it wont shift with out hard acceleration. things i have checked; vacum line, new modulator , gear on governor, valve on gov. and weights on gov. i was told it could be a leaking or open kickdown switch. any one have any thoughts. fluid is not burnt nice red color also. any help would be great thank you