Components of Net Deferred Income Tax Asset (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Sep. 30, 2017
Deferred income tax assets:
Allowance for doubtful accounts	$ 553	$ 784
Inventories	6,938	11,265
Loss and tax credit carry-forwards	21,207	16,293
Stock-based compensation	614	2,147
Accrued product warranty	144	176
Accrued compensated absences	259	419
Property and equipment	457	430
Prepaid income taxes	714
Other reserves	62	134
Deferred Tax Assets, Gross, Total	30,948	31,648
Deferred income tax liabilities:
Allowance for doubtful accounts	(6)	(9)
Intangible assets	(1,681)
Property, plant and equipment and other	(3,681)	(3,158)
Subtotal deferred income tax assets	25,580	28,481
Valuation allowance	(25,379)	(28,259)
Net deferred income tax assets	201	222
U. S.
Deferred income tax assets:
Allowance for doubtful accounts	545	777
Inventories	6,870	11,215
Loss and tax credit carry-forwards	17,056	11,803
Stock-based compensation	614	2,147
Accrued product warranty	136	174
Accrued compensated absences	259	419
Prepaid income taxes	714
Other reserves	56	127
Deferred Tax Assets, Gross, Total	26,250	26,662
Deferred income tax liabilities:
Intangible assets	(1,681)
Property, plant and equipment and other	(3,622)	(3,087)
Subtotal deferred income tax assets	20,947	23,575
Valuation allowance	(20,931)	(23,575)
Net deferred income tax assets	16
Non U. S.
Deferred income tax assets:
Allowance for doubtful accounts	8	7
Inventories	68	50
Loss and tax credit carry-forwards	4,151	4,490
Accrued product warranty	8	2
Property and equipment	457	430
Other reserves	6	7
Deferred Tax Assets, Gross, Total	4,698	4,986
Deferred income tax liabilities:
Allowance for doubtful accounts	(6)	(9)
Property, plant and equipment and other	(59)	(71)
Subtotal deferred income tax assets	4,633	4,906
Valuation allowance	(4,448)	(4,684)
Net deferred income tax assets	$ 185	$ 222