As dodgy as the early Tandy stuff's reputation was as "TRASH-80s", it's no surprise that OP's dad loved them. Back in the day, Tandy machines really did deliver value for money. Of course once you popped them open, their manufacturing-design issues would be revealed. There were bodgewires all over the place because of last-minute issues found after the PCBs had gone to manufacturing. And the ones with built-in CRTs had issues wherein the cathode of the CRT was DANGEROUSLY CLOSE to the main PCB. If you weren't careful cracking that puppy open -- zappo! Fried motherboard, possibly fried you!

For these reasons, and possibly also to hide their shame and embarrassment and make extra scratch on service calls, Tandy equipment often had one of those "Warranty void if seal is broken" stickers on it, which are now illegal to enforce even in the USA. They also used to seal the screwholes with Glyptal to prevent unauthorized tinkering; this so incensed my dad that he called all the way up the chain to the president of Tandy Corp. to make them stop (and also drilled through the Glyptal to get at the screws).

But when it worked, it was solid, not to mention cheap. Great stuff for hobbyists and even small businesses.