Undoubtedly, it's better to contact a specialist.
I have a trillium
4500 Jubilee 1980 and the last season I managed to start the pilot and as soon as I released the valve of safety, it went out.
I visited a specialist and he found the pipe of copper cut by the friction which occurred then travel.
A chance for us, it was the pipe between the safety valve and the furnace.
The specialist corrected the problem, made a check of the system, completed with a good cleaning.
During the ageing of the plumbing for the propane
, the specialist told me, that with years, there is a slender film in pipe and that he is possible, in strength vibration during the travels, that these unstick from the wall of the pipe and find themselves in the tiny jets which feed the fire.
It's may be your problem!!?
Be careful and made beautiful rides with your family.
Do you have a gaz detector ?
Merry christmas to all,