Limey..........? We're Brassed Off....

[Molasar]

are we not straying off the point?
(EDIT: yes mea culpa for going off-topic, don't tell me I already know and apologise.)

the objective is to return it so that it passes an inspection at school.

the objective is not necessarily that we return it in good condition, only that it passes the test of perception of good order for one day only and that is the day the youngster hands it back and the parent gets a receipt for an instrument returned in good order.

the effect of this is that for all we care the bloody thing can turn to dust over the school holiday, it was in the school's care then, so if it happens it's their fuck up.

WD40 may for all I know dissolve the rubber (never heard of that but I'll take it on trust) but it'll take months to do it, so any deterioration will not be noticeable in just a couple of weeks.

my plan of campaign would be, not nore than a week or two before handing it back, to to strip it with WD40, then wash in soapy water a couple of times, then rinse a few times, then reassemble and go over the outer metalwork with the recommended metal polish.
the polish will cover up any residual smell of WD40.

job done, box ticked.