TM  1-1500-204-23-1 b.  Adjustment  of  Windshield  Wiper  System. The windshield wiper system shall be adjusted as follows: Do not operate wipers on dry glass. (1) Loosen  locknut  on  wiper  blade,  align  blade, and tighten locknut. (2)  Remove  locknut  from  wiper  unit  shaft, adjust position of arm on shaft to give full sweep on windshield, and reinstall locknut. (3) Adjust tension nut at base of wiper arm until blade exerts 1 1/2 to 2 pounds pressure against wind- shield. NOTE Measure tension at tip of wiper arm in a direc- tion perpendicular to windshield surface. Drycleaning  solvent  is  flammable  and  solvent vapors are toxic. Use P-D-680, Type II Sol- vent in a well-ventilated area. Keep away from  open  flames.  Avoid  prolonged  solvent contact  with  skin. (g) Remove grease spots with drycleaning solvent, Federal Specification P-D-680. (h) Remove blood stains by use of cold water applied with sponge. Remove residue with a 10 percent solution of ammonia hydroxide, MIL-STD-612, or a paste of cornstarch, Federal Specification NC-541. Allow treated area to dry. When cornstarch is used, brush dried material from fabric. (2) Repair. Repair  and  patch  fabric  material  of troop seats using repair procedures outlined in para- graph 9-22. 9-20. Aircraft Seats. Maintenance  of  aircraft  seats shall be accomplished in accordance with the proce- dures explained in the following paragraphs. a. Troop Seats. Cleaning,  repair  and  installation and  removal  procedures  for  fabric  or  cotton  canvas  troop seats are explained in the following paragraphs. (1) Cleaning. Clean troop seats as follows: (3) Installation and removal. Follow instruc- tions  contained  in  the  applicable  aircraft  maintenance manual for installation and removal procedures. b. Metal Seats. Cleaning, repair, and installation and removal procedures are explained in the following paragraphs. (a) Unfold and place parts face up. (b)   Brush   with   a   firm   bristle   brush   to remove excess dirt. (c) Prepare a cleaning solution of 1 ounce of anionic synthetic detergent (alkyl benzene sulfonate), Federal Specification P-D-410, per gallon of water. (d)  Work  up  heavy  suds  by  repeatedly squeezing  of  a  sponge  saturated  with  detergent  solution. Apply heavy suds to soiled areas. (e) Scrub soiled areas briskly, using a firm bristle brush or heavy cloth. Wipe off with a damp cloth. (f) Allow treated area to dry. Brush to raise nap. Drycleaning  solvent  is  flammable  and  solvent vapors are toxic. Use P-D-680, Type II Sol- vent in a well-ventilated area. Keep away from  open  flames.  Avoid  prolonged  solvent contact  with  skin. (1) Cleaning. Clean with clean cloth moistened with  drycleaning  solvent,  Federal  Specification  P-D-680. (2) Repair Patches and reinforcement repairs to metal seats will be accomplished in accordance with repair procedures in TM 1-1500-204-23-10. (3)  Installation  and  removal.  Follow  instruc- tions  contained  in  the  applicable  aircraft  maintenance manual for installation and removal procedures. 9-43