The factory will always concoct some BS story about how to do simple tasks. Drilling and pulling seals is VERY common. My advice is to coat the drill bit in plenty of grease...this will ctach any shavings. Carefully screw in a couple of self tapers and either lever or pull out the old seal with vice grips. Ensure theres no metal shavings etc, clean everything, lit smear of rubber grease on housing and press the new one in. ALL Triumph seals are standard sizes and are readily available at bearin/seal suppliers for much much cheaper than Triumph supplies them for.
