Does my Bosch WFB 2004 washing machine need fixing?

I have a Bosch WFB 2004 washing machine. There is foam still visible after the last rinse. However, I am perhaps worrying for no good reason because I have downloaded what appears to be an official user manual that says ' Certain detergents tend to produce more suds but this does not affect the rinsing result'. I know I should just accept this but it just does not feel right to see lots of suds after the final rinse. I have always used Persil non biological and no more than recommended although I cannot remember if I have always had a surfit of soap suds. In the past couple of years, I have done a second wash without detergent (uneconomic and unfriendly to the enviroment).