Dear Ray,
your most critical step with Bone marrow smears is good fixation, and a
minimum of 10mins is required on well dried smears using Methanol Anhydrous,
Analar, Univar, Chromotography grade or USP with a water content of <0.05%
by Karl Fischer.
Stain with neat Wrights stain for 3 minutes, make a fresh 1 in 3 or 1 in 4
dilution with Sorensen pH 6.6 or 6.8 buffer and stain for 4-5 minutes.
This slide will be overstained, now differentiate with brief rinsing using
Sorensen Buffer to which has been added  up to 10% Methanol with 1 ml of
Triton X-100 for every 4-5 litres of buffer.  Stop and check using low power
frequently until skills have been polished. Stop differentiation by rinsing
briefly with water. Allow to dry and examine under oil, or coverslip with
DPX or Entellan.

Note:- Under no circumstances rely on the Methanol in your Wright's to carry
out your fixation. Under no circumstances use Ethanol for Fixation.
You mention you use a Wright/Giemsa, this sounds awefully like the
terminology used by Bayer/Ames/Hematek for their stain pack, if you are
using their machine and stain, put the slide through the machine twice
(After you fix slide) then remove excess stain and background with the
Differentiating buffer mentioned above. It can and does work.

Yours in Histology,
Mike Rentsch. Australia.