This is the only one that I have noticed in my collection. The flaw consist of a defect at the top of the left limb of "M". This was first mentioned in the Sarawak Journal of February 1982, page 95 to be precise. It was noted on the horizontal values of 1c, 8c , 50c and possibly other values as well. It was positioned as stamp 29 or R3/9. On the vertical 2c value, it is stamp 25 or R3/5. This is on a sheet of 100, 10 x 10.
For the 1946 issue there is supposed to be a broken crown variety. I will see if I can find a copy somewhere.
Update 6.4.14 Just found this block of 4 with the flaw in a fair in Alfreton, Derbyshire this morning. Also note on the top stamp on the right, we have ? a "tower" amongst the trees.