N Cook wrote:

Not actually required as a mechanical problems on a Marshall "Valvestate"
VS65R. But I cannot find any details on the main components , ready for next
time, or for anyone else coming across them , any pointers ?

Marshall T65 and its compliment T64A (curiously one suffixed A only), TOP66
package Motorola MJF 22 , also marked R91, TO220 package, not found on
Motorola site

TOP66 ? Do you mean TO-220 ?

Resistors in TO-220 packages are not unknown. Possibly low inductance low ohms
type. What's the function - and marking ?

Graham