I got mine from Madvapes:
Chrome Bolt Replacement Switch
It's pretty spendy, at least it seems so. With that, and the 18650 extension I got the thing ended up being more expensive than my Vamo, so that's a little silly. I had also purchased the stock replacement switch, 2 actually, for the regular head. i fixed the old one, but honestly I like the recessed connection head a lot more, so I mainly got it for that.
Although it might be a good idea to make absolutely sure it's your switch before spending that much money. Do you have a multimeter? If you touch one lead to the center pin of the connector, and the other lead to the center pin inside the battery housing area, and depress the switch the resistance it shows should be very low, if the switch is working right, as once pressed ideally a switch becomes as seamless to the circuit as a length of wire would be.
if the switch is bad the resistance should be higher.
Or like I said it could also be a battery that's faulty or something, or maybe even the charger not charging the battery to full capacity. Off the charger the batteries are usually around 4.2v, and shouldn't be used under 3.2v or so. Loosing close to an entire volt when comparing a fully charged to an almost dead battery definitely will affect how your atty/whatever is performing. Pretty big difference in vape quality at 4.2 compared to 3.2. That's the case with any and every mod that isn't regulated though, so not specific to the bolt.
I'm just trying to think of every possible reason yours isn't performing properly, I'd hate to steer you in the wrong direction if it isn't the switch. I can say for a fact the switch on that new head is a lot easier to push than the stock switch, or either of the replacement switches I bought.
I'm actually using my Bolt right now with a tank on top, with a 2.0ohm boge carto in it. The battery is at 3.9v right now and I'm still getting pretty goodperformance. One thing about single battery, non-boosted PVs that I notcied is that they just don't have enough power for dual coil cartos. When using my VW PVs I need to generally set DC cartos a good 4 watts or so higher than I would need to for a single coil of the same resistance, just something to think about.