Since your hydraulic slides appear to be the ones that are making squeaking/squealing sounds I would...
.. Go outside and look at the underneath area of each main slide and look at the two gear packs for each slide
.. If they are all rusted up and dirty then clean them with a brush
.. look at the sides and top of each gear pack guide bar and look for evidence of hard scrapping of the wear tabs against the guide bars
.. Use Lipperts PDF on how to minimize gear pack squeal.. simply process
https://lci-support-doc.s3.amazonaws...cd_0001864.pdf