[JRTJH]

Twist lock light bulbs can sometimes be difficult to insert into the base. This can happen for a couple of reasons that aren't related to "bulb must be built wrong".... First, the two contacts in the base are spring loaded. Sometimes the springs are a bit too strong and won't compress easily. We perceive that as "the bulb is too tight". Second, sometimes the light bulb base is built with lead (or solder) contacts that are a "touch too tall" and the bulb just won't push into the base enough to engage the two tabs. In either situation, sometimes just filing off a part of the lead/solder to "shorten the contact" is all that's needed. When I have a bulb that has a base that's "too long to push into the base" I find a concrete block, rub the two contacts along the concrete for a couple of "swipes", wipe the dust off the base and try again.

Usually, after a couple of "adjustments" the bulb will fit and work properly.

Then again, with the "Made in china" label, most anything is possible, so if this won't work, try another brand of bulb. There may be a "manufacturer's defect", but I'd grind down the contacts a tad before I gave up completely.