Sealed struts and fork magnaflux confusion

[Skybolt]

I am confused by some wording in my airframe logbook, an entry from the year 2013. In the annual writeup are sentences that read: "Sealed struts installed 04-06-1995 at 2852 TTAF. Forks due for magnaflux at 3228.2 TTAF and replacement at 4728.2 TTAF"

I thought that sealed struts were lifetime struts, and that eliminated the inspection requirement for non sealed struts. What's this business about fork inspection and replacement about? Can someone kindly educate me?
Many thanks
Matt

 

[huston marlowe]

 

[Joe G]

 

[bob turner]