stradic 3000 help needed

my stradic is winding the line on to the spool with a bias toward the rear. according to the instructions, washers can be added/removed/adjusted to manipulate the line bias as the owner chooses. i removed the spool and did not see any washers to adjust. questions:
1 - am i looking in the right place for the washers to adjust
2 - i had it worked on last year and it has performed great except for the line bias. could the repair shop have forgotten to reinstall the washers?
tia, i'll hang up and listen except to answer any questions/clarifications