If it’s a Peerless 6 or 800 series ‘box the recommended lubricant was Bentonite grease which, they said, resisted heat build up. What they didn’t say was that it tended to dry out not reach the areas where it was needed. If we ever had to open a ‘box to replace selector keys or bearings we used to refill with a semi-fluid grease. The slight downside to that was that because of the construction with open-ended bushes and no proper seals there was sometimes a little seepage if too light a grade of grease was used. In practice, this was not enough to cause a problem.
As has been said, the noise from the ‘box is probably normal – just not masked by the absent i/c lump.
