Bracpan;
I agree with Arcturus, but to a lesser extent...it does sound like an Ign issue, and those darned Condensers (china's finest!) are known for this kind of failure, so before replacing the entire Distrib for hundreds of dollars, try simply replacing the Condenser for $10! An if you are not yet familiar with the famous Armored Ign Sys on vintage Volvos, Arcturus is absolutely correct about the one-piece assembly. See also:
https://www.sw-em.com/Volvo%20Igniti...rmored%20Cable
Of course, make certain the Points Bolt penetrating the Dist Housing is not loose and/or contacting the Dist body...that would be the simplest fix! See:
https://www.sw-em.com/Volvo%20Igniti...ition%20System
Good Hunting!