I have two of those supplies, well actually the 30V 5A model - 305D. With one of my units the termination to one of the secondary windings on the transformer came loose so when set to certain voltage ranges and the faulty secondary winding was selected the unregulated supply voltage would plummet until the supply dropped out of regulation and the output voltage got so low that it would select a different secondary winding on the transformer which happened to be functional. Then unregulated supply voltage would then shoot up enough for output voltage to come up enough for it to select the faulty winding again and the process would repeat over and over.
I removed the outer insulation on the transformer and found that the transformer has aluminium secondary windings. They had just loosely twisted the copper wiring with the aluminium windings (because you can't solder them). I crimped them properly which fixed the issue.
Another problem I found was that the unregulated voltages were way too high and the pass transistor was burning up a lot of power because of a 20-25 odd volt drop between unregulated supply and output. This is probably a combination of using a different transformer than the circuit was designed for and the increased mains voltage in Australia (normally 240-250Vac).
I reversed engineered the circuit and changed all the set points (by changing resistors) where it switches in different transformer taps so now the worst case is about 12-14V drop.
If your unit does not regulate at any set voltage then you might have blown the pass transistor(s), a fuse or the current shunt (0.15ohm 5watt resistor in my units). I think the only difference between the 305D and the 3010D is that the 10A model has two pass transistors, two current shunt resistors and a bigger transformer. My 305D has unpopulated locations on the PCB for the extra components.
edit: scratch that, looks like you've got some kind of SMPS version
, so my experience probably isn't useful unfortunately. First thing to check would be the switching transistors, mounted to that aluminium heatsink.