If they're the kind of clips that slide up and down in a rail on the sides of the heatsink, you can put one clip in the middle of each side and it will hold well enough. If part of the whole fan assembly then you have to get creative.

My answer

Obviously it’s part of the whole thing 🤣 I’m never THAT lucky!

Maybe some double sided sticky thermal adhesive?

I use double sided carpet tape. It's thin enough and conduct heat enough for a486, to make the heat get to the sink. I admit that thermal tape would be better 😀

Right, ok well guess that’s my first port of call.

Does a 486 cpu get very warm?

According to the consensus any 486 greater than dx2 66 should have an heatsink and fan (they are usually very small), while slower than that people used without any heatsink (they get very warm).
Anyway a small heatsink it is usually fine for 486 era.

If it's a 3.3V CPU you can try without, but a 5V would prefer one for stability at load. i.e. you can "prove us wrong" by booting a 5V without one, but then be back with a "Why does DOOM timedemo crash halfway through??" etc.

edit: I should say that it's Intel DX2s only that might be okay without a sink sometimes, anyone elses, Cyrix, ST, AMD etc, needs one.

Most '66s are 5 V. Should be printed on, for Intel, see this:
Re: 486 VLB motherboard questions

As BitWrangler says, non-Intel will need a heatsink.
Intel, you could try. Might be unstable, won't die on you.
Pretty sure won't need a fan.

I don't like the idea of anything sticky too much. Will mess up the Chip. Plenty of methods to attach the heatsink mechanically. Is it a ZIF socket? Photo couldn't hurt!

Any 5V DX2 will require heatspreader. Later CPUs with 3.3V will work without one.

I should say that it's Intel DX2s only that might be okay without a sink sometimes, anyone elses, Cyrix, ST, AMD etc, needs one.

Intel packaged all retail (Overdrive) DX2 CPUs with a heatspreader.

You can use some fishing line to hold the heatsink onto the CPU. For tightness, use springs attached to the heatsink and then the fishing line hooks to the springs and weaves through the pins on the underside of the CPU.

As for fixing the stock clips, it is probably easier and way less time consuming to just order a replacement cooler.

Had the exact same problem with my DX2/66. Solved it with this tape: https://www.amazon.nl/gp/product/B07MPBFRRH. Works perfectly.

Hey guys i fixed the problem last night, I'll post back later with some pictures and details. I'm probably going to start another thread later, as I need to find the manual for this motherboard. The only reason I knew WHERE to put all the case wires, was because I took photo's before disassembling the computer (few decades of experience taught me that nugget). I still want to consult the manual just for my own benefit, so i know what some of those wires are for as only a few headers on the board are labelled, PC Speaker, Turbo ect..Last night i had brain fog when I came to connect the AT PSU connectors to the header on the board, I had a vague memory of black wires needing to go side by side. But still had to go online, consult an LGR video and watch him build a 486 system. Soon as he reached the PSU part, I was relieved to see that after 23+ years the information was still stored some place in my head 🤣

identifying the motherboard, this is pretty awesome:
https://www.ultimateretro.net/en/motherboards/search

Make sure to post your result, please - I wonder if it's similar to the one in my Escom 486 pizzabox...