Prueba lo siguiente:
DECLARE @str nvarchar(max) = '0150566115,"HEALTH 401K","IC,ON","ICON HEALTH 401K",,,1,08/21/2014'
SELECT
SUBSTRING(@str, 1, CHARINDEX('"', @str, 1) - 1)
+ REPLACE(REPLACE(REPLACE(REPLACE(SUBSTRING(@str, CHARINDEX('"', @str, 1), LEN(@str) - CHARINDEX('"', REVERSE(@str), 1) - CHARINDEX('"', @str, 1) + 2), ',', ' ' + CHAR(7) + ' '), CHAR(7) + ' ', ''), '" "', ','), '"', '')
+ REVERSE(SUBSTRING(REVERSE(@str), 1, CHARINDEX('"', REVERSE(@str), 1) - 1))
--Explaination
--Extracting the portion of the string before the first occurrence of '"'.
DECLARE @part1 nvarchar(max) = SUBSTRING(@str, 1, CHARINDEX('"', @str, 1) - 1)
SELECT
@part1
--String between first and last occurrence of '"' and removing unwanted characters.
DECLARE @part2 nvarchar(max) = SUBSTRING(@str, CHARINDEX('"', @str, 1), LEN(@str) - CHARINDEX('"', REVERSE(@str), 1) - CHARINDEX('"', @str, 1) + 2)
SET @part2 = REPLACE(REPLACE(REPLACE(REPLACE(@part2, ',', ' ' + CHAR(7) + ' '), CHAR(7) + ' ', ''), '" "', ','), '"', '')
SELECT
@part2
--String after the last occurrence of '"'
DECLARE @part3 nvarchar(max) = REVERSE(SUBSTRING(REVERSE(@str), 1, CHARINDEX('"', REVERSE(@str), 1) - 1))
SELECT
@part3
--Concatenation
SELECT
@part1 + @part2 + @part3
HTH!!!
