DETAIL OF SELECTED BALANCE SHEET ACCOUNTS

Allowance for Doubtful Accounts

Activity in our allowance for doubtful accounts receivable consisted of the following (in thousands):



	Three months ended June 30,						Nine months ended June 30,
	2018			2017			2018			2017
Balance at beginning of period	$	264		$	310		$	179		$	811
Bad debt expense (recovery)	18			(129		)	110			(226		)
Uncollectible accounts written off, net of recoveries	(36		)	(92		)	(44		)	(493		)
Change due to foreign currency translation	(7		)	1			(6		)	(2		)
Balance at end of period	$	239		$	90		$	239		$	90

Inventories

The components of inventories are summarized below (in thousands):



	June 30, 2018		September 30, 2017
Raw materials, parts and subassemblies, net	$	21,402	$	17,848
Work-in-progress	1,452		600
Total inventories	$	22,854	$	18,448

Cost and Estimated Earnings on Uncompleted Contracts

The components of costs and estimated earnings and related amounts billed on uncompleted contracts are summarized below (in thousands):



	June 30, 2018			September 30, 2017
Costs incurred on uncompleted contracts	$	823,190		$	987,164
Estimated earnings	246,852			316,970
	1,070,042			1,304,134
Less: Billings to date	(1,038,540		)	(1,278,746		)
Net underbilled position	$	31,502		$	25,388
Included in the accompanying balance sheets under the following captions:
Costs and estimated earnings in excess of billings on uncompleted contracts	$	70,939		$	51,554
Billings in excess of costs and estimated earnings on uncompleted contracts	(39,437		)	(26,166		)
Net underbilled position	$	31,502		$	25,388

Accrued Product Warranty

Activity in our product warranty accrual consisted of the following (in thousands):



	Three months ended June 30,						Nine months ended June 30,
	2018			2017			2018			2017
Balance at beginning of period	$	2,241		$	3,649		$	3,174		$	4,639
Increase in warranty expense	1,036			593			970			1,313
Deduction for warranty charges	(891		)	(949		)	(1,752		)	(2,618		)
Change due to foreign currency translation	(23		)	39			(29		)	(2		)
Balance at end of period	$	2,363		$	3,332		$	2,363		$	3,332