'Recapping' is something you do on 70 year old valve equipment, not on a relatively modern TV from a manufacturer that has a reputation for using high quality electrolytics. If a capacitor
IS actually domed, then it should be changed regardless - but you haven't posted a picture of it? - some types of capacitors do look slightly domed anyway.
I presume you have little test equipment?, and no experience repairing TVs?.
I opened up the tv and after discharging CRT
As that is a complete rookie thing to do - you've actually increased your chances of getting a shock from the CRT, when you had zero chance before, as you weren't working anywhere near it. Repairing around 30-50 TV's per week I'd probably only discharge the CRT on one or two per month, if that. You should also be aware, if you're concerned about the CRT?, that once you've discharged it, it will almost certainly charge back up to a certain extent.
So presumably you don't have an ESR meter? (essential for testing electrolytic capacitors), or an oscilloscope which can do the same, but with the set powered up. If you do have a scope, then C664 can easily be checked by clipping the scope on R619 (easy point to clip the scope probe on), and checking how much ripple there is (there should be
VERY little).
As it's a thermally intermittent fault, a can of freezer spray may help you locate the fault? - wait until the set has started working OK, then spray the various PCB's in turn, seeing if you can find aboard that when cooled reintroduces the fault.