Equipment Care & Repair

Finding the Right Replacement Part: Diagrams and Part Numbers

How to identify the exact OEM part you need: model and serial numbers, reading exploded diagrams, and what to send us when you're not sure.

Updated · 2 min read

Ordering the wrong part costs a week. Most wrong orders come from one of three things: the wrong model, a serial-number revision, or confusing a diagram's item number with the part number. Here's how to avoid all three.

1. Find the model and serial number

Every correct part order starts with knowing exactly which machine you have.

  • Look for the data plate or sticker on the frame, motor housing or handle. It lists the model and serial number.
  • Write down both. Manufacturers revise machines over time, and parts can change between serial ranges. National publishes manuals by serial range (for example, "SN: 7700-100523 - 7700-100572") for exactly this reason.[1]
  • If the plate is gone, photograph the machine from all sides. We can usually identify the model from photos, but only the serial pins down the revision.

2. Use the exploded diagram

The diagram shows you where the part sits and gives you the number to order.

  1. Open the parts page for your machine. Our parts pages are organized by brand and model, with diagrams grouped by assembly (motor, pump, handle, cutting head).
  2. Find the part on the diagram. Note its item number (the callout on the drawing).
  3. Match the item number to the parts list to get the part number. Order by part number, not item number.
  4. Check quantity. Some items are sold individually, some in packs.

3. Order the parts that go with it

One part rarely comes off alone. Order what comes off with it in the same shipment.

  • Seals, O-rings and gaskets are one-time-use. Replace them with anything you take apart.
  • Replace wear parts in pairs where they work in pairs: wheels, bearings, brushes.
  • Fasteners strip. A few spare bolts are cheaper than a second shipment.

Where to start

Our parts pages are organized by brand and model.

When you're not sure

Send us the model, serial number, a photo of the part and a photo of where it sits on the machine. Contact us and we'll confirm the part number before you order.

Common mistakes

Most wrong part orders come from the same few mix-ups.

  • Ordering by the diagram callout. Item 12 on one drawing isn't item 12 on another.
  • Ignoring the serial range. Two machines with the same model name can take different pumps or boards.
  • Reusing seals. A reused O-ring is a leak you'll fix twice.

Related guides

These maintenance guides help you catch wear before it turns into a parts order.

References

  1. National Flooring Equipment: Manuals and resources by model and serial range

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OEM replacement parts, organized by assembly, with the manual for each machine.