In my messing about with modern telly' from the tip days, I had a few duff LOPT's, the little Vestel 14" portables badged Bush or Alba seemed to have problems, I had 2 (actually still got one!) where EHT would arc out of the transformer to the core, or as it preferred, my fingers if they got anywhere near! The set usually shut down instantly or at least very soon after trying to turn it on, normally with one or two loud snaps! I bodged the one I still have with araldite, which worked but you could still hear some crackling going on and the occasional loud snap followed by the set shutting down. I should really try and get a new Lopty for it one day.. Grandata did sell a replacement, but I never got round to ordering it. I also had a Daewoo portable go the same way, I remember fitting a new horizontal output transistor and powering up only to watch the Lopty arc violently and blow the transistor again.
I have a Roadstar 10" portable that had a duff transformer too, it had melted on the side and split open, must have been shorted, the set still powered up but the line whistle was quiet and no picture would appear, the transistor was ok but got hot very quickly.
All the replacements I did buy were the yellow box HR ones, never had any problems with them
Regards,
Lloyd