Have you already replaced the capacitors in the cluster?
That I would do first. They play

when the caps are at the end of their lifetime. Only a few $ investment to buy them and to solder them in, anyone (almost) can do that , or ask a radio repair shop to do it for you. Detailed descirption is on Johan and Sean's page, link on my website below.
up to 2/89:
old cluster (with grey backplate) with coding plug in the cable loom
2/89 to 9/90:
1. Redesign -> cluster (with white backplate) with coding plug in cluster
from 9/90:
2. Redesign -> cluster (with blue backplate) with coding plug in cluster
In a car built up to 2/89 all 3 variants fit
From 2/89 you can only use clusters with 1st and 2nd redesign
BUT: the coding plug must always exactly fit the the special design variant of the cluster. It cannot be changed.
That means, do not force an EPROM inside. If it does not fit, it is the wrong cluster.