After another few days of playing with postures, I have finally broken the left calf which is a slim link. Drilled a 1mm hole and fix with copper wire and instant glue. Clean up some of the seam lines at the same time.
Applied two thin layers of Tamiya Primer of ABS/PP on the frame, followed by two thin layers of Tamiya TS-64 dark blue. I did not apply surfacer as I don't want the paint to be too thick which might affect the movability. As a result, the surface of the paint isn't very smooth. It is acceptable as the frame is made of softer material (ABS / PP) and most of it cannot be seen once built up.
The good news is the frame is still movable after the paint job and it is still holding up.