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I'll add these comments.
1) The hydraulic system. I don't believe needs any maintenance. Mine since '05 and used often works fine. No need to change oil or check level.
2) The bow metal mechanism. Here, yes there are "bars" the move, joined with rivets or nut/ bolt , and I have lubricated with drops of motor oil every so often over the years. Be care not to over lube and stain the top of interior.
3) In other words, lube any thing have a joint and moves, can not be a bad thing to do.
You may also wish to look toward the tonnoue (sp) cover, truck separator panel and any sensors to insure all are aligned and tight.
There is also a TSB on the straps the pull the top to keep it from hitting the tonnoue during its opening & closing operation.