From your report, I am assuming that you have a good 50 ohm dummy load (Heath Cantenna, Drake/Vectronic/MFJ 100 - 150 dummy load).
You can always test your tunes on a reliable tube tester. Neutralization should always be perfromed when you "change" tubes in this transceiver (instructions in your user manual - abailable from Kenwood or one of the manual services).
"I have aligned the coil pack"
I don't understand this statement
Without proper test equipment "twiddling" with adjustable coils and capacitors in LC circuits or the filter section is a fools game.
There could be a component failure or value change that is causing you symptoms in the 20 and 10 meter sections of the transmit chain.
Call your local amateur store's service department or if you don't have a local store, drop an e-mail to Cliff at AVVID Clif@avvid.comhttp://www.avvid.com/
Reasonable rates. Can get you back on the air with full power on 20 and 10 meters (and re-align the receiver).