Various issues around the head being porous.
I know the Co-op had porous-head problems with the completely-different head on the contemporary TSS
, the TSX has the same 2-valve head as other 750 and 650 twins.
Some special non standard engine parts
In a TSX?
Compared to a '79 triumph these look fat and bloated.
"... eye of the beholder" and/or the images? I saw 'em (in both black and the red) in the metal when they were new; nice-looking bikes imho.
The redeeming feature was of course the electric start but as usual it was under powered and unreliable.
It depends ...
An educated guess says your tour around the wonderful WWW didn't take you to any of the Triumph triple-related pages, where many owners have related that exactly the same Lucas
M3 starts big-bore one-litre triples (not bad for something first used (designed?) sixty years ago for 125 and 250 scooters)?
Having lived with one electric-start triple for over forty years, a second for only five years less, and sorted out several owned by other people, ime the people bitching about them on the wonderful WWW either have never owned one in their lives or are Twerentmes ("T'weren't me"). E.g. one of the more common problems for several years is, because Triumph failed to mention it explicitly in "Routine Maintenance", some owners are completely flabbergasted when their thirty-to-forty-year-old completely untouched starter either won't spin the engine very fast or won't work at all ...
Otoh, with hindsight, using the camshaft drive gears to electric-start a 750 twin was possibly not the best choice ...
Aiui, as each piece in the train broke, Meriden designed a stronger replacement; they'd reached the crankcases when they ran out of money ... But, given when TSX's were built, any reason to assume one for sale wouldn't have the latest stronger bits in it?