I know this is a strange question, but is anybody aware of Humax models that will allow a centre cut out screen.

I have an old Humax PVR attached to a computer monitor which is itself built into a 1955 HMV television. The PVR plays up a bit, I think that perhaps the tuners are not totally compatible with modern signals. Frequently in middle of playback the sound will stop although vision continues, it carries on for a little while and then just as suddenly the sound will catch up with the visionary. It is at its worst on BBC channels and Channel 4.

OR is there any way of updating the old boxes?

Thanks in advance for any help.