Brunton compasses are the industry standard in lensatic compasses, although the company does manufacture more elementary orienteering tools. As the company has been manufacturing its standard line of compasses for decades, there are numerous differences in materials and style that have arisen through the years. However, most Brunton lensatic compasses have the same basic construction, and repair procedures are the same throughout.
Test all functions and make notes of irregularities. Test to see that the needle will settle at north within 10 seconds. Fully extend all hinges and make sure they will maintain their desired position.
Remove all external screws on the body of the compass starting with the small screw to the left of the bezel that locks the dial into place. If internal mechanisms are faulty or "sticky," open the bezel by removing the lock ring of its outer circumference with a fine pick tool. On newer compasses, this ring is made of rubber, but on older models it is a steel ring that must be carefully pried where the ends of the ring meet.
Remove the compass needle by lifting it from its pin. A slow needle should be re-magnetised. Older needles are a single piece of steel that can be strengthened by being rubbed over a permanent magnet, while newer needles incorporate two small bar magnets that must be serviced with a magnetizer or replaced outright.
Press the rider gear on the side of the case (the "rider" is the dial the corrects for magnetic deviation) out of the compass from within, then gently lift out the rider. If the inclination bearing is gritty it should be removed for thorough cleaning by taking out the screw that holds it to the bottom of the case. On some models it will be necessary to remove the needle pin by carefully turning it counterclockwise with pliers or a wrench.
Clean all removed components as thoroughly as possible using rubbing alcohol and cotton swabs or a lint-free paper towel. Inspect the rider cogs for irregularities. Most Brunton compasses use soft brass screws to avoid damaging the compass with over-torquing, so inspect all screws for uniform pitch and replace them with identical screws from a hardware store as necessary.
Clean the internal space of the compass as thoroughly as possible with rubbing alcohol. Install all removed components in the reverse order of disassembly, checking the functionality of each component before moving on. If the hinges are persistently loose, apply automotive thread locker to the screws and tighten them as much as possible. As a last resort, apply a very small amount of strong adhesive to the hinge pins to create friction.
Write down each step you take while disassembling the compass so you can remember the correct procedures for installing them. Most compasses use screws of different sizes, so keep each screw labelled with its respective component. To remove and install the glass bezel, it may helpful to use a gummy product such as Blu-Tack or Silly Putty. If there are any non-functional parts, it may be worthwhile to acquire another non-functioning compass for spares as many models have interchangeable parts.