Never tried to fix this radio, I cannot find manuals and the traditional CB source, CB Tricks is down.
However, here is what I would do;
Clean the board with isopropyl alcohol and a cheap solder flux brush or old toothbrush. Clean and check the push to talk button and all switches.
Mark all of the adjustable cans in line with the screwdriver slot in case you miss-align one. Do not attempt to align yet, you do not know which ones are transmit and which are receive.
Look at all the solder joints and re-solder anything that looks slightly bad. A lot of problems are just bad component connections.
If you can, while listening to an active channel, push on the components and see if you can narrow down any problem, sometimes pushing on part of the board will tell you where the problem is.
Replace ALL of the electrolytic caps if you can. ("The Usual Suspects")
Check the antenna connection even though Transmit works, maybe try a long wire attached to the antenna....
These are things you can do without any electronic tools, I do not know if you have any, so start with these suggestions.
Maybe another similar Midland radio has schematics and maybe you can find something, several radios were slightly altered and a new number was assigned...