Dr.RenalNash said:

Update: the thing I was blaming turned out not to be the cause.

Adding a me-too, because a thread of one person's experience is not much use. Posting only so the count is not one.

Dr.RenalNash said:

Update: the thing I was blaming turned out not to be the cause.

There is a second half to this that has not been said yet. Whatever the answer turns out to be, the method for getting there is the same: state the assumption, do the arithmetic in public, and invite the correction. That is slower than asserting, and it is the only version that survives being wrong.

One concrete data point for the thread. Practical: whatever you change, write down the date and the reason. In three months the reason is what you will have forgotten, and the reason is what makes the record worth having.

A narrower follow-up, since the general answer is now clear:

How long did you give it before you decided it was working?

hank_denver said:

Practical: whatever you change, write down the date and the reason.

Careful with the causal language. Two things moving together in a period when five things changed is not a mechanism, and stating it as one makes the thread less useful to somebody reading it later.