Benjamin 342 in 5.5 (.22) and Sheridan C9 series acquired; need help, please

Found in old hunting lodge; both have crisp bolts and triggers and fair wood; as expected, no pressure builds when pumping.  I've restored many long guns but these are my first air rifles; any advice much appreciated: seems simple although I've not pushed out the pins of the arm of air cylinder.  Thank you for this site.  - Bryant