Stock 89 audio system common issue repair and weird FM tuning issue

[89SE]

My 89 Grand Prix was not in use for many years, the radio degraded in that time. It started to give a lot of pops and bangs. So much it seems to have blown a front speaker in the few moments it has been turned on. The speaker is an easy fix, just remove the dash pad and screw a new one in (16054362 is replaced by 15173233 and can be easily found).

My system is a 4 speaker with Remote control head 16075882, the optional Cassette+equalizer 16050912 and steering wheel controls. The amp and receiver (16072780) which is located above the glovebox is the one that typically causes issues. I found the documentation here on the forum, unfortunatley the link for the amp doesn't work anymore:

But even better than documentation, I found a common cause and fix for the pops and bangs: I tried exactly this procedure: https://reattaowner.com/roj/component/content/article?id=198:radio-capacitor-replacement-instructions. The 6 green capacitors were indeed shot. I found d4x5mm (not d5x5mm), 1uF, 50V, 105°C replacement capacitors at RS and had a specialist to put them in. The radio now works well, only some very minor pops are still noticable when the volume is turned to 0.

I am very happy with the result and recommend this fix. However, I did notice now that my FM tuner apparently only goes up to 104.05MHz... Scanning, or manual tuning to get past 104 make it jump to the bottom of the frequency band again.

I wonder if anyone else had a similar issue or fix for this?