Thought I'd share this with the rest of the forum (thanks to David 'Mick' Taylor from the Facebook Rive pages)
If you loose the end cap(s) from the D36 legs you can either buy 2 for £3.77 from a Rive dealer or as I did bought 6 from eBay for £2 inc P&P They are a really tight fit and being 35mm shouldn't pop off when removing accessories.