[TenTec] TT Centurion

[Doyle]

GE,
    I have a new matched pair of 3-500Z tubes that I am going to install in my TT Centurion.  Was wondering if it is necessary to run the tubes (filaments only) for a while with no HV.  If so for how long?
    One other question.  I am driving the Centurion with an Omni VI, when operating sometimes the receive does not return & have to key the Omni to recover the receive.  I see the output relay in the Centurion it has a black cover over it.  How do you remove the cover so I can clean the relay contacts.  When operating the Omni barefoot, no problem with the receive.

Thanks,

Doyle/N4VV