I had the same problem with ash build up where my fire would only last 3 days. I finally got a daily technique down where I could keep the fire going; thanks to this forum.
This is the document I made up for myself and my wife. I do it once in the morning and once in the evening.
A High Heat Foil Back Insulation
B Heat Outlet
• 20"x 20" (480EK)
• 18"x 18" (365EK)
C Double Wall Back
D Heavy 7 Gauge Steel
E 6" Flu
F Filter Box with Side Mounted Air Filter (Optional)
G Large, Energy Efficient 3-Speed Blower
H Fire Brick Lining with Cast Iron End Plates
I Cast Iron Shaker Grates (Optional)
J Shaker Grate Handle
K Pre-wired Electrical Components Standard
L Baked Enamel Metal Cabinet
M Secondary Heat Exchanger
N Secondary Bypass Rod
O Airtight Cast Iron Feed Door
P All 1/4" Steel Door Frame
Q Heavy Cast Iron Ash Pit Door
R Large Removable Ash Pan
S Draft Control, Forced or Automatic (Manual on 365EK)
1. Turn OFF Forced Air Draft switch (S)
2. Open Ash Pit Door (Q)
3. Empty ash pan if full (R)
4. Pull open Secondary Bypass Rod (N)
5. Crack open coal feed door (O) for 10 seconds, then open fully.
6. Using fireplace poker, poke deep into coals till you hit bottom of shaker grate making new air passages and breakup bottom layer of ash; about 6 places.
7. Shake grate using Shaker Grate Handle (J) till you get a good red glow from under the grate and letting the fine ash fall down into the pan.
8. Push (Bank) coal towards rear of fire box, tapering down towards the front of box.
9. Fill tapered void with coal up to top of fire brick, leaving hot coals exposed in rear.
10. Close coal feed door (O)
11. Push closed Secondary Bypass Rod (N)
12. Close Ash Pit Door (Q) and fully open Ash Pit Draft knob or leave Ash Pit Door (Q) open for 15 minutes so newly added coal will catch.
(SET TIMER AS REMINDER)
13. Close Ash Pit Draft knob or close Ash Pit Door (Q).
14. Turn ON Forced Air Draft switch (S)