@giddy,
If you require service parts - filters/plugs/element and related staff you can get them at kirinyaga road shops like commercial & equipment,Legacy auto parts.
If however you want other parts i.e non service parts which you would not normally replace for instance a windbreaker,a replacement door,locks e.t.c you can check out industrial area shops like shamas.
'The same sun that melts the wax,hardens the clay' - Niger