The through bolts should not be tightened enough to pinch the end bushings against the mounting tabs. just tight enough to prevent any front to back movement. The end bushing are intended to center the through bolt in the a-arm tube. The a-arm bushing should rotate freely on the through bolt. that's why it's important to get grease on that bolt.
Trimming a touch off the zerk fitting does cause the spring and check ball to fall out but the hole is so small, grease packed into the zerk forms a seal so no measurable amount of contamination gets in. You do get a lot of crud in from the ends around the through bolt so a shot of grease pushes the dirt back out. Hit the zerk with a grease gun until you see clean fresh grease squeeze out from around the bushing ends, wipe the dirty grease off and your done.
zerks have a tapered thread and are self tapping so the correct size drill bit is important. Tapping the holes will aid in setting the zerk. Assemble the a-arm with the bushings and inner sleave in place, clamp in a vise or use a c-clamp to hold it all together then drill the tube and inner space at the same time. Remove the inner spacer and enlarge that hole so it can shift around and center it's self without hanging on the zerk end when the end bushings are pressed in. Remove any burrs and make sure it will spin on the bolt without binding. A rat tail file is needed inside the spacer sleeve to clean it up. If you align the spacer hole with the tube hole before running in the zerk allows for a little extra clearance for the zerk length. you can zap those boo-boo holes with the welder sand them smooth and use the rat tail to clean up the interior, then you can start fresh.
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