I've just repaired my Thetford hand pumped toilet flusher and there was a thin line of sealant under the pump casement ( like blue tac rolled into a thin worm ) what is it best to replace it with please as i have broken it.
I assume you mean the bead that was beneath the top cover/handle enclosure. I too have recently repaired the hand pump and found I could easily re-use the same sealant by carefully removing and re-applying same.
Father-in-law however, following a similar repair, applied some plumbers mait such as this from Screwfix