TV QAM questions

[stingray230sx]

hope this is in correct forum.
I have 2 older tv's.
one in my spare "office" room Sanyo FVM 3982
no cable box but I subscribe to suddenlink [optimum] with internet and cable tv.
on the Sanyo I get all the channels that I get on the cable box in my bedroom, though its a bit off, as channel 131 is on 9.1 / channel 126 is 19.1 / channel 139 is 19.2 but after a while I remember so no big deal.
I routinely watch these channels and a few more later at night, but recently the cable box bedroom tv [ Element PLX 4202B] started having issues only on those same higher numbered channels.
It will go to a blank screen, then come back and blank again, and basically the channels are un watchable as the blanking never stops. This has been ongoing for a while, but recently it has gotten so bad I cant watch these 6 channels I frequently want to view.
I tried the standard unplug the cable box power cord, and one night left it off over night to no success.
So, saturday I sat back and called the cable company, expecting a long wait, but suprisingly they picked up fast.
after they listened to my problem, which while talking to them it went blank no less than 5 times, they put me on hold then after a few minutes came back saying there were no signal issues, and I should pull my box and return it to the local store for a free exchange.
so I did, knowing I should be able to connect the coax directly to the Element tv, as with the Sanyo and still get my channels, just no guide etc.I have been wanting to do this as I am refurbing a house to move into and I will prob buy a 3rd tv, and will want 2 of them on the coax only or maybe all 3 as I don't dvr or pay per view so I can live without the guide as there are online resources to view the channel descriptions.
So, the issue that has come up is that once directly on the coax, the Element tv after doing the channel search, will not display or "find" the 6 channels that were blanking out thru the cable tuner box.
Am I correct in assuming the Element tv's QAM tuner is just crude and wont pick these channels up? I have tried several phrases in searching, and come across where cable companies are encrypting the channels, but I do still get them on the Sanyo or maybe it is a coax issue? I know about 6 years ago I had a problem with the same rooms reception thru the box, in that one channel was just blank, and it took 3 technicians to finally figure out there was a problem up the street on the top of a pole in a junction box.
I was hoping the channels would be there in that bedroom so I could verify that the box was the issue, as in the "spare" room where the channels are on the direct coax connected Sanyo they do not blank out or otherwise have issues.

thanks for any advice and sorry for the novel length diatribe.....

 

[stingray230sx]

just an update, I dug into my spare tv cable crap box.
had a couple of "modern" splitters from that time I was afraid my coax from the attic to the 2 bedrooms was acting up, but was the junction box on the pole up the street.
I put a splitter on the cable from the closet, then a short section of coax to the tv.
rescanned for channels and picked up 3 of the missing channels.
but even straight to the tv these channels that were "going blank" momentarily but constantly, now constantly freeze up, so the digital box was just blanking versus the freeze up of the straight cable.
figure the tuner box is ok.
I am of the belief that there is a signal issue coming into the house causing this, but getting the non-Optimum techs to fix it, even acknowledge it may be difficult.