That's viridian with an "i". Three in fact.
Think of the circuit as a water pipe. If the water flow is restricted at the beginning of the pipe, it will be slow at the end. Likewise, if it is restricted at the end, it really doesn't matter how much water can flow into the beginning.
So yes, absolutely, change all of the caps. Oil caps will have more body, no doubt about it, but they require about 100-200 hours of break in. If you purchase the Russian K-40Y caps, they will probably only cost around $8.00 each. Pretty reasonable. You can always splash out on Jensen copper foil or AmpOhm if the budget is a bit bigger.
But again, the power supply is going to be the most important issue. Address the electrolytic power supply filter caps on the board. You may be able to replace them with film caps like Solens, but even if you have to go electrolytic, go better. Have a look into those diodes, that may be the biggest issue that you have.
Think of the circuit as a water pipe. If the water flow is restricted at the beginning of the pipe, it will be slow at the end. Likewise, if it is restricted at the end, it really doesn't matter how much water can flow into the beginning.
So yes, absolutely, change all of the caps. Oil caps will have more body, no doubt about it, but they require about 100-200 hours of break in. If you purchase the Russian K-40Y caps, they will probably only cost around $8.00 each. Pretty reasonable. You can always splash out on Jensen copper foil or AmpOhm if the budget is a bit bigger.
But again, the power supply is going to be the most important issue. Address the electrolytic power supply filter caps on the board. You may be able to replace them with film caps like Solens, but even if you have to go electrolytic, go better. Have a look into those diodes, that may be the biggest issue that you have.

