I have to take shallow cuts even with brass and aluminum.
Can I ask what DOC you consider to be shallow?
I had to completely disassemble debur, clean and locktite everything
I don't know about using locktite but eh, this is really a slightly bigger Chinese mini-lathe.
Disassembly, deburring, cleaning and adjustment to a greater or lesser extent (depending on the importer; Warco in the UK, for example, by most accounts do a better job of having their import products more immediately useable) is to be expected really.
There are loads of videos on YouTube pretty much showing the preparatory steps one needs to take in varying degrees of fussiness.
There are also plenty of videos about improving the capability and rigidity at not great expense, and some just using tools like a drill press and hand tools.
Needless to say, none of these Chinese bench mounted lathes are Colchesters, Harrisons, or Southbends; one has to be prepared to work within the limitations of these machines or go bigger. Then again, to a greater or lesser extent, that's true of all machine tools. Nobody is going to be turning gin palace prop shafts on a Colchester Student
It seems to me that the key with buying import lathes is picking the right importer, understanding the preparatory setup steps one will have to take and knowing the limitations of the machine.