So, it doesn't do this on LSB, does it?
A carrier on only one sideband points to the 10.695 MHz (nominal) carrier oscillator.
One quick way to tell is to listen to the, ah, "pitch" of the noise in each SSB mode.
Ideally, the hiss you get on an empty channel should sound the same on upper as it does on lower sideband.
The pitch of the 'hiss' you hear in SSB mode is a hint. If it sounds a lot lower on one sideband, the carrier-frequency setting for that mode has been set too close to the SSB filter's frequency. Allows too much carrier to leak through. Also tends to give the receiver's empty-channel "hiss" sound a low pitch.
There is also a trimpot that serves to balance out the carrier in SSB modes. VR7 is set for minimum carrier in sideband transmit, with the mike gain set at zero.
If this fixes your problem, that was simple.
If you can hear a big difference in the pitch of the empty-channel hiss between USB and LSB, that points to the carrier oscillator. Has a trimmer coil for AM, USB, and LSB.
The last 3 steps in this alignment page cover the carrier crystal.
http://www.cbtricks.com/radios/rci/rci_2950/rci2950_pll_adj.htm
But you need a way to measure the frequency of the carrier-crystal's oscillator to set those.
73
