Welcome, @Bobh, Glad you found us.
I'm not a tech, but there are some here that may respond. Just a heads-up that this is a volunteer community of Carver afficianado's and fans..., not really a tech support site - although there are many technical threads of work, restorations, refreshes and repairs for many many Carver components - that's what the volunteer aspect is.
We welcome you to start thread on your repair and contribute to the community with your diagnosis and repair. That will likely get more volunteers to pipe in over the next few days/weeks.
Most of the techs that are members here are in business, and don't visit that often - they are just swamped with Carver and non-Carver work as I understand it. There are some hobbyist techs too that are exceptionally skilled, they are likely the first to respond, if they can.
FWIW, the MXR-130 is a beloved receiver, and there are many examples of restorations and repairs in the forums. You could browse the receiver section, or use the SEARCH function - that will also help guide your research..., beware, there is a LOT hear, and search will give you lots of threads to peruse..., and may take time.
Again, welcome, glad you found us, and enjoy the deep resources here in the threads.
Oh, btw, do you have the docs and schematics for the MXR-130 to work from? If not, check out the manuals library (top of page, main menu "Manuals and Specsheets".