I'm fairly sure that an exact replacement of just the faulty one ( 70HF40 ) would fix it.
You can get one from http://www.mouser.co.uk for £4.80, but the delivery charge is £12. Personally, I would buy two of these: http://www.ebay.co.uk/itm/262315860092. They are 70HFL80, with very slightly different characteristics, so you would need a pair.
You can get one from http://www.mouser.co.uk for £4.80, but the delivery charge is £12. Personally, I would buy two of these: http://www.ebay.co.uk/itm/262315860092. They are 70HFL80, with very slightly different characteristics, so you would need a pair.