I have just bought a second hand Ridgeback MX20 for my daughter and I have noticed there is a slight play in the bottom bracket (wiggling the cranks I can feel it, and on the chainring side i can see the chainring moving a bit). Is it important to get this sorted quickly? Would I be able to take the bottom bracket apart, regrease the bearings and tighten it back up or does it need a new bottom bracket?