LEASES - Components of lease expense (Details) - USD ($)	3 Months Ended	9 Months Ended
	Jan. 31, 2020	Jan. 31, 2020
LEASES
Operating lease expense	$ 155,000	$ 408,000
Amortization of right-to-use assets	11,000	34,000
Interest on lease liabilities	1,000	5,000
Total finance lease expense	12,000	39,000
Total lease expense	$ 167,000	$ 447,000