Also, I see you are AI-ing this,
'Later Years: After losing his original Plexi in an airline shipment in late 1978, he relied on replacement Marshalls and eventually shifted to modified Marshalls and later the Peavey 5150 for most touring applications, though he continued to use his Plexi for studio recordings until 1991'.
You see, the bit that is left out is the reason he quit taking it out on tour and quit using it in the studio.
Why do you think that was?
Wrong.
The amp didn't sound like it used to any longer. Hence all the people that were employed to fix it. Practically everybody and their brother. Including Friedman at the end there who got the same transformers even as his, I think they were like one number off or something. John Suhr, when he had it, said that it hadn't been touched at all. All of the soldering was intact, untouched.
Friedman accounts for the difference in tone, between Eddie's Marshall and other ones that were around that time, to just a few specific parts.
But even still, when it was so called fixed, it wasn't. Eddie never used it again
* Also 'late '78 tracks. Texas Jam was July 1st 1978