[TenTec] Titan 425 power supply woes

[A R]

After more than three years of faithful, dependable service, the 9425 power supply gave up. T-shhoting revealed that R2 on the 81212 Rectifier had opened (big crater).
According to the manual schematic, R2 should be 470 ohms, and (again, according to the schematic notes) 1/2 watt. The pwb accommodation for R2 sure isn't appropriate for a 1/2W resistor.
The failed R2 in this supply is a 25 watt wirewound 20 ohm resistor.
Sure would like to know what the correct R2 resistor (resistance and power) is.
There may be an underlying problemthat caused R2 to fail, but all the related electrolytics associated with R2 (C4, C5, and C6) show no visual evidence of failure (leaking or swelling).
Any help with establishing the correct value of R2 would sure be appreciated.
Access to replace R2 is labor-intensive, so if it is REALLY a 20 ohm, 25W resistor, it will definitely get replaced by a chassis mounted resistor that's more accessible.
Thanks in advance for any help.
73,
Allen--W7GIF