My average purchase price for SanDisk is high, so please advise whether I should buy more to average down and exit, or if it is better to just stay put.

I think it will trade sideways for a few months like it is now, then rise starting around the end of the year and reach its previous high. If it were me, I'd lower my average cost by buying in installments when it's low and just wait.

Buy in installments. Then, when it rebounds, sell what you bought at the high to lower your average price. Looking back later, you'll be glad you didn't sell. When entering, you bravely buy at the top thinking it's a good price, but when it crashes, you're in pain and want to cut your losses, and now you're too scared to buy more; then, if it rebounds again, you ask if you missed the bus, buy at the peak again, and get trapped. Let's do the opposite instead.

If you think it won't go up anymore, you should sell off, and if you think it will go up, you should keep investing. If you just chase the price and constantly worry about whether it goes up or down, you will ultimately fail.

I wrote a comment about the SanDisk entry point, so go look for it.

Aim for the end of the year and buy slowly, bit by bit. Also, set aside money so you can buy even if it drops below 1000.

Buy in installments. In the long run, it's not a bad price right now, but buy in tranches considering that it could fall further.