Slotted holes - centre marks on drawings?

Hi,

Im having trouble with centre marks in slots.  I have created a part (refer attached jpegs) with a series of slotted holes.  To create the series, I created one slot, patterned it down one side of the part, then because it was a symmetrical set of slots, mirrored the slot and slot pattern to the opposite side.

Im having troubles with my drawing, some slots will put a centre mark at the centre of the slot, others will only put a centre mark at each of the arced ends (refer attached jpeg).  How can I get centre marks at the centre of each slot on all slots?

Thanks,

Dana

SolidworksDrawings And Detailing