Whether some are relevant to the issues relating to low rail adhesion or not, Nexus have put tenders out for a range of items.

There are 17(?) lots included in those tenders, are training for chainsaw use and track welding.
Other tenders include lift and escalator maintenance.

Presumably staff will be trained internally to carry out maintenance and tasks going forward, rather than staff brought by private contractors, carrying out work on Nexus behalf.