Roof valley leak

[Sonic70]

Found triangular tile piece near bottom valley has mortar cracked and water was tracking inside on its back edge, was thinking of cutting corner slightly of tile straight so
It cannot track along back edge.

 

[Sonic70]

Am going to strip out valley in warmer weather, remove and check all tiles for damage, do 1 inch deep v cut in fascia board for valley. Have found same valleys from merchant so will not have to take up valley battons. Recut valley tiles on right side as I don't think they overhang valley enough. Not sure weather to drop fascia board height or not either side of valley. Any thoughts?

 

[Sonic70]

Just noticed in the loft that valley is of layboard construction but there are no boards under the valley supporting it that go between rafters, is this correct as I thought valley needed boards to support it.