Common measurement issues happen with These TDK Epcos Ceralink SP capacitors this will help you measure correctly and reference correct values to
This is a common problem.
They need to reference the C(0) from the datasheet on the top of page 3:
So the capacitances they should be measureing are 6.5µF ± 20%, and 1.5µF ± 20% respectively for the 500V and 900V parts.
Also there are two capacitors internal to this construction and they need to make sure to measure them both connected in parallel.
This is seen on page
So it would be necessary to connect the + terminal pins indicated above together in order to place the two internal capacitors in parallel.
Lastly, it is important to respect the polaraity indicated because the capacitors do retain a residual polarization from final testing at the factory and the capacitance in reverse polarity would be about 15% less.