SRAM Guide T Caliper Service Manual page 12

Remove the piston seals from each caliper body half. Install new seals
9
inside each caliper body half.
⚠ WARNI NG
Do not scratch the seal gland with the pick. Scratches could cause fluid
to leak when the brake is applied, which will contaminate the brake
pads and could lead to a brake failure.
Pick 20 mm or 15 mm Thru Axle
Caliper Piston Removal 12