I can't speak for the WIT Color or DX5 heads on Chinese printers but I have a printer with Spectra 255 heads and have a similar problem. The heads simply aren't close enough to the caps to seal properly. The caps are the rubber kind where you put solvent in them to keep the heads wet. Since the alignment isn't perfect that doesn't work but the solution I found is just getting a cloth (we use a silicon based one) and putting solvent onto that and then putting the cloth between the caps and the head.
I know, I know...not much of a solution but it works, the heads don't clog. Probably won't work for you since the DX5s have that positive pressure thing with their capping station but worth considering doing something like this as a workaround so you don't lose nozzles on your heads until you figure out a better solution.
Hope it helps