Hanging tiles held on by flashing tape

I have a small dormer with hanging tiles on the triangular bit above the window.

Flashing tape runs along the top 2 edges of the tiles, however part of this has come away together with 2 triangular shaped half tiles from the top edge which had been held in place by the tape.

Should I be trying to fasten these part tiles before re-taping (if so, how?) or should I just use the tape to hold them like before?

Thanks...

I`d give gripfill or pinkgrip a go or sticks like sh8t..........yes it`s really called that

Thanks - I'll give that a go.