Condensed Consolidated Statements of Changes In Stockholders' Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Total
Balance (in shares) at Dec. 29, 2019	8,331
Balance at Dec. 29, 2019	$ 8	$ 297,073	$ (283,258)	$ 13,823
Common stock issued under stock plans and employee stock purchase plan (in shares)	52
Common stock issued under stock plans and employee stock purchase plan	$ 0	(25)	0	(25)
Net loss	0	0	(3,165)	(3,165)
Stock-based compensation	$ 0	(398)	0	(398)
Balance (in shares) at Mar. 29, 2020	8,383
Balance at Mar. 29, 2020	$ 8	296,650	(286,423)	10,235
Balance (in shares) at Dec. 29, 2019	8,331
Balance at Dec. 29, 2019	$ 8	297,073	(283,258)	13,823
Net loss				(6,144)
Balance (in shares) at Jun. 28, 2020	10,912
Balance at Jun. 28, 2020	$ 11	305,013	(289,402)	15,622
Balance (in shares) at Mar. 29, 2020	8,383
Balance at Mar. 29, 2020	$ 8	296,650	(286,423)	10,235
Common stock issued under stock plans and employee stock purchase plan (in shares)	29
Common stock issued under stock plans and employee stock purchase plan	$ 0	(31)	0	(31)
Stock-based compensation	0	741	0	741
Net loss	$ 0	0	(2,979)	(2,979)
Common stock offering, net of issuance costs of $1.1 million (in shares)	2,500
Common stock offering, net of issuance costs of $1.1 million	$ 3	7,653	0	7,656
Balance (in shares) at Jun. 28, 2020	10,912
Balance at Jun. 28, 2020	$ 11	305,013	(289,402)	15,622
Balance (in shares) at Jan. 03, 2021	11,094
Balance at Jan. 03, 2021	$ 11	306,885	(294,409)	12,487
Common stock issued under stock plans and employee stock purchase plan (in shares)	354
Common stock issued under stock plans and employee stock purchase plan	$ 0	(484)	0	(484)
Stock-based compensation	0	368	0	368
Net loss	$ 0	0	(1,689)	(1,689)
Balance (in shares) at Apr. 04, 2021	11,448
Balance at Apr. 04, 2021	$ 11	306,769	(296,098)	10,682
Balance (in shares) at Jan. 03, 2021	11,094
Balance at Jan. 03, 2021	$ 11	306,885	(294,409)	12,487
Net loss				(3,751)
Balance (in shares) at Jul. 04, 2021	11,512
Balance at Jul. 04, 2021	$ 12	307,117	(298,160)	8,969
Balance (in shares) at Apr. 04, 2021	11,448
Balance at Apr. 04, 2021	$ 11	306,769	(296,098)	10,682
Common stock issued under stock plans and employee stock purchase plan (in shares)	64
Common stock issued under stock plans and employee stock purchase plan	$ 1	146	0	147
Stock-based compensation	0	202	0	202
Net loss	$ 0	0	(2,062)	(2,062)
Balance (in shares) at Jul. 04, 2021	11,512
Balance at Jul. 04, 2021	$ 12	$ 307,117	$ (298,160)	$ 8,969