Perhaps the RAF should let the BGA and LAA look after its maintenance requirements, as all the evidence would indicate that the BGA and LAA do a better job (although to be honest the RAF have set that particular bar pretty low).
However if the maintenance folks mess up and/or lose and/or fail to update the paperwork they would still be in the same mess.
I have it on reliable authority that the first Viking to be returned to service from Southern Sailplanes was billed to the taxpayer at a figure in excess of £100,000 New ASK21s are around €80,000 to buy.
However the ATC won't get more than a handful at most new K21s delivered per year, and delivered they cost quite a bit more especially if VAT has to be paid. For example a tailwheel is an optional extra! You have to add on for instruments as well.
Also the K21 isn't immune from paperwork failings...
Schleicher can sell more K21s than they can build, they are happy with it like that, and they won't devote several years production to dig the ATC out of a hole.