Schedule II - Valuation and Qualifying accounts (Details) - Allowance for Doubtful Accounts [Member] - USD ($)		12 Months Ended
		Dec. 28, 2019		Dec. 29, 2018
Valuation and qualifying accounts information [Abstract]
Balance at beginning of period		$ 680,000		$ 470,000
Charged to costs and expenses		202,000		220,000
Charged to other accounts - Describe		78,000	[1]	0
Deductions - Describe	[2]	0		10,000
Balance at end of period		$ 556,000		$ 680,000

[1] Acquired company opening balance.

[2] Uncollectible accounts written off, net of recoveries.