My tech has had my 83 Spoiler for a while because 5 of the inlays are lifting out of the fretboard. He is unsure of how he should fix this issue. The inlays are plastic and the new ones are real Mother of Pearl so replacing the 5 would not look correct, any advice would be appreciated.

A single spot of superglue either on the inlay or the wood and firm pressure for about a minute.
One came of mine years ago so I did the above.
Are they damaged?, if they have not completely come off then gently lever them up and apply the superglue.
Don't apply too much as it leaks out onto the fretboard when pressure is applied

Thanks for the reply I told my tech what you did and he is going to give it a try.

Terry's suggestion is what we'd do. Short of replacing all the inlays so they match, it's at least worth a try.