On my 2000 Heritage bike 2 of my piston rod covers are leaking oil from the top. I asked the dealer to fix them. They had my bike 3 days and they just tightened them but they still leak. The dealer says it´s a big job (expensive) to replace these because a lot of the engine must be removed taking many hours. Is this right ? I would assume it´s best to replace all 4 at the same time, even if only 2 of them are leaking.