Yes, you can replace pallet jack parts yourself if you have basic mechanical skills and the right tools. Many parts, such as wheels, handles, and hydraulic seals, are designed for easy replacement. Manufacturers often provide manuals or guides that detail the replacement process, which can be helpful. 
However, there are a few considerations to keep in mind:
1. **Safety**: Ensure the pallet jack is not under load and is on a stable surface before starting any repairs. Use appropriate safety gear, such as gloves and safety glasses.
2. **Tools**: Basic tools like wrenches, screwdrivers, and pliers are typically needed. Some parts may require specific tools, so check the manual or part specifications.
3. **Parts Compatibility**: Ensure that the replacement parts are compatible with your specific model. Using incorrect parts can lead to malfunction or damage.
4. **Complex Repairs**: For more complex issues, such as hydraulic system repairs or electrical components in powered pallet jacks, it might be better to consult a professional. These repairs can be intricate and require specialized knowledge.
5. **Warranty Considerations**: If your pallet jack is under warranty, check the terms. DIY repairs might void the warranty, so it might be better to have a professional handle the repairs in such cases.
6. **Time and Cost**: Consider the time and cost involved. While DIY repairs can save money, they can also be time-consuming if you're not familiar with the process.
In summary, for simple repairs and replacements, doing it yourself is feasible. For more complex issues or if you're unsure, hiring a professional is advisable to ensure safety and proper functioning.