Yaesu FT-847 Modification Manual page 16

Anyway if nothing wrong can be seen, just good idea will be to re solder the
points, especially the coils legs. Nothing to lose, but (possibly) way to avoid further
troubles.
On the next pic You can see the points for examination.
At the end of PA job, another good idea. As observed in all four 847 after some
(years) of time beryllium oxide paste used as heat spreader on transistors is getting
dry and hard.
NOTE: I found that in 847 year model 8G there was NO thermal paste AT ALL –
hard to say why? Maybe they forgot to apply before inserting the PA into
chassis?
All we need is to clean transistor places and their base, apply small amount of
ceramic thermal paste same as used in PC.