NOT meths then which is residually greasy. Isopropylalcohol (IPA) cleans the grease away lovely. I used to cut an emery board to fit between the ceramics on linear Halogen fittings. vibration is the killer for lamps that are not cooled properly.
Thought people might be interested in an update on this one. I didn't post earlier, because as I posted on a superstition thread onetime, I have a fear of putting the hex on things, so I thought I'd leave it awhile but...it's now been working fine for a couple of months, without a blowout.
Here's what I did. Following suggestions, I decided to try thoroughly cleaning the contacts. But how? They're awful narrow holes that the wee wires go into...
After pondering it for a bit, I decided to use an old bulb, roughen up the pins as much as I could with a bit of emery paper, then dip them in isopropyl alcohol and shove them in, out, in, out, in, out, with a bit more dipping and a bit of added wiggling, and...like I say, it seems to have done the trick. I post this in case anything along these lines ever happens to you - might be worth a try.