The meter and relays flicker because the voltage that feeds them is low. But now we need to ask ourselves, why is it low?
Start at the source. Battery. Grab your volt meter and test the battery voltage with the key off. You're looking for 12.6 to 12.9v. Then have someone turn the key to start. Watch the voltage. If it drops below 9.5 volts, it's junk.
If it does not drop that much, then you have a connection problem. Battery cable or ground cable. Or as Kubota calls them, plus cord or earth cord.