Thermal paste for amp heat sink?

Hi, I have a Rockford Fosgate punch 150 one channel was sounding distorted (fuse was blown) replaced with a new one 6 amp. So it works good. But this is not the problem I took the whole circuit board out of the sink and I didn't feel comfortable puttng it back in because the white compound was all dried. What if I put it back in? Will the transistors short out due to the white compound being dried? Or should I put some new heat sink paste? Thanks