HAM international VIKING II keying by itself

[thor_212002]

I have a HAM international VIKING II that starts keying itself as soon as I turn it on, it was OK a minute before, I checked SWR on a Dummy load, turn off, disconnect, turn on and it began, BAN BANG BANG, I tried removing the Mic thinking it was a stuck or shorting PTT but it kept doing it, where should I begin checking, any Ideas?

[ch25]

tx/rx switching transistor