I made exactly those same mods to my identical sander. Larger motor and better fence.
My attitude to much of the stuff from the orient is to regard it as a kit of parts only assembled with chewing gum screws to keep it together for transport. Dismantling, sometimes remachining, cleaning and reassembly with real fasteners should all be regarded as part of the buying experience. Bought with that viewpoint there is often little to complain about.
A recent example, for quite a while I had a cheap variable angle vice for the mill or drill. It had served me OK for a while but I had a job which was fairly critical so I checked the vice out first. It was terrible. The hinge pin was way out of wack both horizontally and vertically. The fixed vice jaw and the base weren't square to anything etc. A couple of hours machining and general playing about had it in excellent shape. Of course the best solution is to always buy best quality tools, and several decades back when I had a business making race motorcycle chassis I found that it was the most expensive quality tools that were the ones that made the most money. However, now all my workshop work is for me alone with no question of earning money from it and the economics of tool purchase are very different. Although sometimes I lash out and spend a bit more. I have a couple of Indian made boring heads and they have worked reasonably well, even though one needed a bit of fettling first. About a year ago I bought a near new Narex boring head at over 20x the price of the Indian ones. At the time i thought about what else I could have spent the money on, but that is forgotten now and I don't think about that when using the tool, it is so much nicer. No regrets, after all it's only money, right?