Panasonic AJ-Series issues

[ARC Tech-109]

I have a 755 that has this oscillating issue with the tension on the supply reel, it's a lmost like it's trying to overcompensate before it begins to jerk and throw an E64 error. I'm not familiar enough with the Panasonic and keep striking out on a service manual.
I also have a AJ-HD150 with a dead power supply. It pulses like it's trying to start up so I replaced several shorted caps but despite my efforts its still a no-go.
I also aquired a pair of the D230 decks with what I assume are worn heads. If I select DVCAM format run a DVCAM tape it plays well but a native DV format tape will go blocky from the errors before going E-01 low RF. I recall the DV track width was 1/2 that of the Sony DVCAM format so this is where I drew my conclusion. Are these heads replaced as a unit with the motor or as just the upper cylinder?

I'm not very fond of the modern Panasonic "pro" equipment but I do have a need for them so thoughts or suggestions would be appreciated.
Thanks in advance.

(retired) Arc-Tech 109