Plenty on both trucks that might be good spares.
Unfortunately, maintaining a spare parts ware-house requires money & staff.
CFS lacks both.
<speculation based on rubbing shoulders with assorted public servants over many years>...
CFS is probably actively discouraged by public service financial "best practice"
from operating any contingency budget lines other than fire response. So the more
expensive option (commercial new parts & fit) gets the nod. Easier in Department
of Finance Land to account for "replacing something that broke" than for "just
in case".
Also much easier for the Minister to explain to the media in a 3 second sound grab
when some cub reporter goes on a muck-raking expedition, armed solely with SA
Chamber of Commerce dogmas.