Old scope repair question

[Everton]

Hi,

I own a (very) old Telequipment D1010 (analog) scope which until yesterday seemed to be working fine, but out of the blue the normal trigger mode stopped working.  Instead of getting a normal trace, I am getting a dot on the left side of the screen.  This is consistent on both channels and is independent of any other settings.  Also, if I change the trigger mode to Auto or TV then the scope appears to work fine.  Similarly, if I press the beam finder button this works too.

That being the case, I know that both the vertical and horizontal amplifiers should be working fine and so the problem has to lie in the trigger or blanking circuits.  What I am unclear about is how the normal trigger mode works in these old scopes.  Is the trace supposed to stay on the left hand side of the screen until a trigger happens at which time the sweep is initiated, or should the display be blanked until a trigger is present?  I would guess the latter, but am not sure. 

Any help would be appreciated.

Thanks

[Whuffo]

Your service manual is here:

http://www.eserviceinfo.com/download.php?fileid=38278