OK, add a table, I called it PartSort, but you can change it if you have a different name in mind. I put in 10 digit increments, so if you want to add stuff between you have some room to do that without changing the other sort numbers.
Here is the modified qryPartsUsageUnion Query
Then in your report, in the Sort, change the first group sort to PartSort.
Code:
PartType PartSort
Battery 10
Air Filter 20
Fuel Filter 30
Oil Filter 40
Deck Belt 50
Hydro Belt 60
PTO Belt 70
Code:
SELECT PartSort.PartSort, USAGE.*
FROM (SELECT * FROM sbqryUseBattery
UNION
SELECT * FROM sbqryUseBeltsDeck
UNION
SELECT * FROM sbqryUseBeltsHydro
UNION
SELECT * FROM sbqryUseBeltsPTO
UNION
SELECT * FROM sbqryUseFiltersAir
UNION
SELECT * FROM sbqryUseFiltersFuel
UNION SELECT * FROM sbqryUseFiltersOil
WHERE PartType IN ('Belts', 'Battery', 'Filters')
) AS [USAGE] LEFT JOIN PARTSORT ON USAGE.PartType = PARTSORT.PartType
ORDER BY PartSort.PartSort;