Hilti DX 351 M&E Manual page 33

8.3 Servicing the tool
Service the tool in the following situations:
▶ If energy fluctuations occur (evidenced by irregularities in fastener penetration depth).
▶ If cartridge misfires occur (the cartridge is not fired).
▶ If the tool becomes noticeably less easy to operate:
▶ If the required contact pressure increases noticeably.
▶ If triggering resistance increases.
▶ If the adjuster for driving energy is stiff.
▶ If the cartridge strip is difficult to remove.
8.4 Cleaning fastening tool 11,
1. Disassemble the fastening tool. → page 22
2. Clean the fastener guide (bore and thread of the locking sleeve).
3. Clean the cartridge barrel with the cleaning rod supplied for the purpose.
4. Clean the outside and inside of the piston guide (rear of the piston guide), cartridge chamber (1) and hole
for power regulation (2) in the end face of the piston guide.
Do not use a metal brush to clean the O-ring and do not accidentally remove the O-ring. Metal
brushes can damage the O-ring.
5. Lightly oil the inside of the piston guide.
6. Check O-ring (3) for wear and damage and check that the O-ring is correctly seated.
7. Oil the outside of the piston guide or alternatively oil the inside of the locking sleeve.
8. Clean the inside and outside of the power-tool housing.
8.5 Additional checks in the course of the tool service
WARNING
Risk of injury! A faulty piston brake, piston or fastener guide leads to an increased risk of malfunctions.
▶ Check the piston brake and piston for wear and replace them if damaged.
▶ Do not tamper with or modify the piston.
▶ Do not attempt to repair a faulty piston yourself, for example by grinding the tip.
1. Replace the piston if you establish that any one of the following points applies:
▶ The piston is broken.
▶ The piston is badly worn or chipped (e.g. a segment of more than 90° of the circumferential
ring-shaped elevation at the piston tip broken away)
▶ The piston is bent (check by rolling the piston on a smooth, flat surface).
2. Replace the piston brake if you establish that any one of the following points applies:
▶ The metal ring of the piston brake is broken or detached.
▶ The piston brake no longer holds on the fastener guide.
▶ The rubber is badly worn at certain points under the metal ring.
▶ Piston jams in piston brake.
8.6 Final check of the fastening tool
▶ After carrying out care and maintenance, check that all protective and safety devices are fitted and that
they function faultlessly.
9 Troubleshooting
9.1 Problems with the fastening tool
Before you start troubleshooting, make sure there are no cartridges and no fasteners in the fastening
tool. If the cartridges cannot be removed, contact Hilti Service.
If the trouble you are experiencing is not listed in this table or you are unable to rectify the problem by
yourself, please contact Hilti Service.
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