First, I must say some years ago, I was looking for an affordable alternative to Arca Swiss and Arcatech and RRS were the front runners - until I read a few very detailed and very positive reviews of the Markins Q10. I was about to pony up for a Kangrinponche equivalent but when I discovered that the Markins was about the same price but there were far more positive reviews, I got the Markins instead. In actual fact back then I could not find any positive reviews of the Kangrinponche although two of my friends swore that they were great. For me, its the best Chinese made ballheads but the price is quite high in comparison to its competitors.
In any case, going back to your PC-33NS - When you mention the ability to lock without camera movements after, are you referring to vibration or creep? Vibration dampening has to do with many factors - not just the weight capacity of the head but also the ballhead size, the horizontal extension length of the camera and lens etc. The vibration frequency of the tripod also plays a part. If the head is able to lock tight but the movement is vibration, its not a ballhead issue per se. It could be wrong size head and wrong weight capacity of the tripod.
However, if there is creep of the head under its full capacity, then its a different issue. If so, I personally would go back to the retailer and show them the problem of the ball head not locking with the load under 30Kg. I did not realise that this was your problem (I did not see it in your earlier post). This I would agree to be totally unacceptable.
I recall PhotoClam gives a 3 year warranty (longer than any other ball head I know) as to quality and this sounds to me its a quality problem with the head they sold you. Again, mine does not creep and if it did, I would go back to the supplier and demand a swop. If they did not, the whole of the photographic internet community should hear of it.
I hope you will proceed to seek redress for the problems to your ballhead. The retailer's response or support should be of interest to others here looking and considering this brand.