PRC Struts Not Rebounding

I'm a newbie to the group, but with prior TC experience (see my new member introduction post). I have a 42k mike 88 that's experiencing an odd PRC issue. Even after 34+ years, PRC still functions. However, when in firm, at least one front strut (possibly both) don't rebound after compressing from bumps and/or braking. They remain compressed and then "pop" back up to correct ride height when PRC comes out of firm. When not in firm, the struts function as designed.  I'm curious if anyone has experienced this and could provide suggestions or feedback. Thanks.

SOFA

Just a wild guess....... the strut or struts have lost their high pressure gas charge over the last 35+ years. I replaced my PRC struts / shocks last summer with NOS ones I bought back in 2003. One of the old front struts I removed still had gas pressure and would quickly rebound to fully extended. Other front strut did nothing. I could fully extend it, fully compress it, etc and it just stayed in whatever position I put it in.