The Teachers and Educational Workers Union (TEWU) at the KNUST has carried through its industrial action, withdrawing about 70 percent of services on campus.They are demanding correction of disparities and distortions in the grading structure for members under the Single Spine Salary Structure.Members converged at the main entrance of the university, Tuesday morning, to hoist red flag to signify commencement of the strike.Some members were in red shirts and arm-bands, carrying placards with varied inscriptions to demonstrate their grievances.Local Union Chairman, Charles Arthur told Luv Fm about 70 percent of services have been withdrawn. Some essential services, including medical, sanitation and accounts, have been retained.Mr. Aurthur said the action will continue unless the Fair Wages and Salaries Commission (FWSC) resume negotiations to review the grading structure and restore other allowances to members of the Union.The members are demanding risk allowance, cashiers' allowance, electricity subsidy allowance, hospital allowance among others.The TEWU action has yet to impact on academic work on campus.