I've moved the trace on X axes in order to show you this also the weird
vertical trace at the beginning of sweep.
Hope to ear from you.
Jose
At the back of the scope there is a BNC marked as A-gate. While applying your sine wave to channel 1, triggering on channel 1, connect A-gate to channel 2. Pick "chop". Move X-axis to see the beginning of waveforms. You should not see the rising edge of the A-gate. Similarly if you look at A-sweep (available at the BNC back of the scope), you should see a linear ramp starting from the beginning of the trace. If you can see some portion of the A-gate while it is low or rising, blanking may have a problem. If A-gate is OK but ramp looks strange then could be something with the ramp.
I have a 485 and tried this, I can send you the screen shots.
Jittery waveform needs to be debugged separately. If you have another scope look at A-gate and the input signal at the same time to see if A sweep always starts at the same point of waveform. You should also try external trigger (BNC at the right bottom) feeding same signal to both Ch1 and "Ext Trig" and choosing Ext (start with Ext/10 if you are applying 5Vpp).
Ozan
