MO8 Sticky keys/Questions

All,

I recently acquired a used MO8 for free! It had a few broken keys, most of which I fixed but two have quickly broken again (One that I replaced and a new one).
My questions include, what lubricant should I use when I put the new keys on, is there a way to help ensure this doesn’t keep happening?, and would the keybed from a yamaha s90es work for a MO8? They are both listed as BHE keybeds, but I wasn’t sure if they are interchangable.

Thanks!