The stuffing box nut has a recess that holds the packing. Its the
distance from the shaft to the inner surface of the recess that matters.
It can be hard to measure - you may need trial and error. You
normally put three layers of packing into the cup. If it doesn't look
like you can, I suspect there is old packing still in the cup, which
you will need to dig out. You cut the packing at an angle for each
layer, so the ends miter into each other. You arrange the joints to
be at different positions - usually about 120 degrees apart.

Once you tighten things up, it will still leak until the packing sets
and you get the right tension. It will run hot at first while the
packing is setting.

I run mine so it does not drip at all when not running, and drips a
few times a minute when running. You must have a drip when running - the
water lubricates the bearing surface.

Good luck.
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