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Note 5 - Product Warranties (Tables)
6 Months Ended
Apr. 30, 2020
Notes Tables  
Schedule of Product Warranty Liability [Table Text Block]
   

Six Months Ended

 
   

April 30,

 
   

2020

   

2019

 

Balance at beginning of period

  $ 120,000     $ 180,000  

Liabilities accrued for warranties issued during the period

    92,769       153,981  

Warranty claims and costs paid during the period

    (46,389 )     (176,554 )

Changes in liability for pre-existing warranties during the period

    (81,380 )     2,573  

Balance at end of period

  $ 85,000     $ 160,000