Picked up this beautiful sansui 27" the other day!

I have a question for y’all though. I was a complete idiot, and had this in my hatch back. I was on a hill and started off and I did not have the TV as stable as I should have and it tipped face forward and hit my back window pretty hard at about 45 degree angle (amazingly nothing broke). I was terrified I broke it but thankfully it works fine, except that when its a cold startup it has horizontal Lines on the top 4" or so. After about 5 minutes they Go away . I’m almost positive this is my fault although maybe it was already doing that, previous owner didn’t say ofc. I’m wondering, is there a fix for this or should I leave it? Will it get worse overtime ? I’m not new to electronic work (guitar tube amps, tape machines etc) but in this situation I’m not sure the best way. (Pic is when warmed up)

I can post a pic of the lines tomorrow. Really hope I didn’t fuck this thing up :(