They look different to each other and different to the rest in the machine.  The majority are "black beast" type.  I thought generally you would replace the lot?  I'll wait for a price from Mark and see. 

As Chuck mentioned - Coils either work or they don't. The only time they can feel like they are not working is either physical resistance, or if the EOS is not adjusted correctly, they get warm, weak and then blow the flipper fuse..

If the coil part number is not the same as in the manual - they replace them. More powerful coils lead to plastics being damaged. What part numbers do they have printed on the coils ?