So called R ch went intermittant for ages and now permanently low , not
distorted, volume.
Swapping over the PA modules shows problem is between wherever the
signal is still common and where it is split to L And R in the mixer stage.
At least the schema is out there, but anyone been here before.
Twizzle sticking shows up no change.
Bargraph shows correct output level. Next thing to check after sending
this is whether the Monitor Out levels are correct and check the schema
for L&R bypass sw and any other switches between mixer and PAs

The REC out lines are near enough at master vol pot tops and 2 lines at
an interboard connector are near enough at wipers.
RECs out much the same but big difference on signal on the other so a
failed pot.
Got inside and some crud inside. Used by buskers , 500 W this is so
rated by Yamaha, they use an 80Ah sports use battery. So a Stagepas
would be the most efficient way of gettiing your MegaWatt for carrying
your Ah.
Some reticulated foam will go inside the air inlet grill , and tell them
to keep it clean .
I've only previously dealt with PAs of the 300W Stagepas, and again the
PAs are a treat to get to in the 500 , mixer of course like any other
mixer to get into