Revenue Recognition and Related Costs - Disaggregation of Company's Net Revenue by Major Source (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Disaggregation of Revenue [Line Items]
Net revenue	$ 25,551,000	$ 27,877,000	$ 92,245,000	$ 84,204,000
Equipment Sales [Member] | Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Net revenue	11,624,000	11,309,000	33,837,000	23,022,000
Equipment Sales [Member] | Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Net revenue	6,958,000	9,012,000	31,533,000	37,105,000
Parts and Component Sales [Member]
Disaggregation of Revenue [Line Items]
Net revenue	5,208,000	6,317,000	21,595,000	19,445,000
Freight Revenue [Member]
Disaggregation of Revenue [Line Items]
Net revenue	1,597,000	1,141,000	4,494,000	4,141,000
Other [Member]
Disaggregation of Revenue [Line Items]
Net revenue	$ 164,000	$ 98,000	$ 786,000	$ 491,000