Rocker Valve Cover NUTS!!!

About 2 months ago I changed the rocker cover gasket. All has been good since then but for a long run up to Edingburgh I decided to replace the engine soundproof cover over the rocker cover.

When I got back I noticed a sh** load of oil on the drive. Looking in the engine bay the centre of the three bolts holding the rocker cover on has threaded itself whilst under the cover then just worked loose hence the oil shower! :doh:

How can I sort this out? Is it a re-tap and replace with over size bolts or will I have to use something like a helicoil to sort this out?

Thanks

Matt

'97 Disco1 / 300tdi

there are 3 x 88 mm stud that are screwed into head ,rocker cover is held by 3 x nut which can be replaced as well as studs ,if threads in head worn they could easily be helicoiled been careful with swarf i presume its 300tdi