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INVESTMENT IN MORION, INC. (Details) - Morion Inc [Member] - USD ($)
3 Months Ended 9 Months Ended
Jan. 31, 2021
Jan. 31, 2020
Jan. 31, 2021
Jan. 31, 2020
INVESTMENT IN MORION, INC. (Details) [Line Items]        
Cost Method Investment Ownership Percentage 4.60%   4.60%  
Cost Method Investments $ 800,000   $ 800,000  
Related Party Transaction, Purchases from Related Party $ 199,000 $ 332,000 467,000 $ 712,000
Revenue from Related Parties       49,000
Proceeds from Dividends Received   $ 125,000 $ 105,000 $ 250,000