Any help would be appreciated. I have to change the head gasket on my 1973 triumph tr7. I recently purchased this bike and I am totally new to motorcycle mechanics. I am going through the manual trying to figure out what seals and gaskets to order and in the manual it says that when I remove the push rod cover tubes I have to renew the rubber seals. Ok, I found those. As I read on the manual tells me I also need new 'O' rings. I sourced new top 'O' rings. Can I use them on the bottom as well? If not, where can I get bottom 'O' rings? I apologize if this subject has been discussed already.