Firstly, if in doubt you should use/consult a qualified gas engineer for any gas work.
However, notwithstanding that, replacing these pigtails isn't too onerous.
I have a Truma Secure Motion regulator in my MH plus I also have 2 x Truma Securemotion pigtails...which is overkill really as I now have double secure motion cover as it were.
As they are coming to the end of their 5 year life (I believe it is recommended to change them every 5 years: each are date stamped) I have bought 2 standard ones now. If you google 'Truma calor gas pigtail'
you should find wheat you are after. NB: At the moment the Caravan & Motorhome Club have these on special offer to members at around £10 each...that's £7 cheaper than recommended retail (plus £4 postage though). Failing that Ebay is normally your friend!
...if you want to use the gas whilst on the move. Personally I would...
- get a gas safe engineer in to check your installation and see if you can find out if the secure motion regulator has been disconnected for any reason. Once fixed and usable you can use standard pigtails as above.
- Or, if you don't do that then you will need
Personally I only use Truma pigtails and only buy brand new. There are other makes on the market but I trust Truma. There are second hand ones on the market but I personally wouldn't mess around with those just to save a fiver or so. I also believe that you can buy stainless steel pigtails which are good for 20 years but since we change our MH after 4-5 years, I stick with the standard orange ones.
There are loads of experienced MHers on this forum so I'm happy to be corrected if any of the above is wrong.
EDITED TO ADD: See Tugboats really useful post below regarding regulators. This needs to be sorted/checked first before you worry about pigtail