scratchy sound from tweeter

Hi everybody reading this. Love music but have not a clue about electronics. Since my arthritis stopped me from playing piano and guitar I now listen to vinyl from my old vintage system. Fisher Studio Standard - CA-880 and small Relistic minimus speakers. I bed you laugh now but hey - I am on a small retirement budget.

Sometimes I like to crank the music up (loss of hearing helps doing so). Now a problem occurred while listening. Mostly the left speaker makes a scratchy sound especial when volume goes up.
But there is also a bit scratch in the right one but about 90% less. I changed to wires to reverse left and right speaker to check.

I first thought it could be the 1980's amp condensers. (They might could benefit from a replacement too)
Since the left speaker was observed to have a problem I changed the tweeters in both speakers.
But the problem is still there. It feels when the amp gets warm it increases the scratch.
Question: Is it possible that only the crossover in the left speaker is bad ???
Thanks upfrontPuu