Indesit WIA121 washing machineH?

Hi i have the above washing machine that when spins makes some noise and rattles.I looked inside the washing machine and the counter weight concrete block is loose which is attached with 3 large bolts,2 of the bolts are set quite deep down and awkward to get into,can anyone give me advice what type of tool to use to tighten these bolts and how to get into the ones that are deep set many thanks in advance