[TenTec] centurion sticks in transmit

[james]

Hello i have a centurion amp,as i switch the standby operate sw to
standby,and back and forth the red transmit light ligths and stays on till i
switch the standby  operate sw a few times, and it goes off also a 160 mils
plate cur..just as u dead key it the idel cur..,,this also happens sometimes
as i`am talking  but flip the operate sw ,,,,a few times and it goes out
this does noy happen every time  may 50% of time  any help would be
app...thanks harold n5tog