Cisco RNG150N STB no video for first few minutes

When we turn on the STB (Cisco RNG150N) there is usually no video nor audio for the first 4-8 minutes. The video usually does come right on for a few times after a power on/off cycle, but then it reverts to no video for few min after turning on.

Sometimes right after turning on there will be a flash of 1-2 sec of video, then it goes blank for a few minutes and most of the time come back before 10 min are up.

Sometimes I have to re-boot it before the video comes back (after waiting about 10 min) but even then after it does it's POST and guide download there is still a delay before video (and audio) come back. After a power cycle it does behave well as mentioned, but reverts to bad box behaviour.

Is the STB dying?  the singnal bad?

Do i need to record the STB status and signal strengths?

Can I just walk into a Comcast service center and swap for a new unit?

tia,

Paul