Winchester 101 Problem
 

My Winchester 101 has recently stopped firing the the lower barrel intermittently. It clicks when you pull the trigger but the firing pin is not denting the primer. What do you think is wrong? Does It need a cleaning or should I send it to a gunsmith to fix it? Any recommendations for a gunsmith? I live in Edmonton.
Thanks guys.

Before doing anything else, I'd clean it thoroughly. By that I mean disassemble completely, including the firing pins, clean and lubricate, check that the firing pin springs and hammer springs are not broken or weak and see if the problem persists.

I would be giving the mechanism a good cleaning and inspection, and go from there.

Generally the dirt you can see
 

Looking at an over under will not prevent it from firing. We cleaned one (Beretta BL4) that had been malfunctioning recently by removing stock and there was 30-40 years or more of powder dust and bits of plastic off factory shells in the mechanism behind the receiver that is hidden when the stock is assembled.

Dr. B; had a similar problem with firearm in the past, it was a broken firing pin that sometimes seemed to aligned and other time not so much. Good luck finding a gunsmith, David Henry in Bentley comes to mind but I don't know if he still does this type of work.
PM if you wanna catch up on old times.

Old style 101s have a couple of quirks
1. They tend to collect lots of sh1t and the shoulders of the firing pins which might impede a clean strike - take off the stock and check
2. The springs get tired. If this is a Kodensha built 101 it is at least 30 years old. Brownells carries springs and pins pretty cheap
3. 101s don't like Federal 209A primers

Any time I ever had a misfire it was always in the bottom barrel (still is with a "new" Model 101)

There are several factors that may cause a bottom barrel on an O/U to miss fire .

Dirty
broken firing pin
piled up firing pin return spring
deformed hammer and/or firing pin
firing pin hole deformed
weak / broken hammer spring

The geometry of the bottom firing pin is lower on the pivot point which the nose of the firing can get swept by the barrel upon opening if return spring not working properly .
The hammer has less arc on the bottom firing pin than the top firing and everything being "right " is more critical on a bottom firing pin than the top.

One other problem on inertial trigger if you shoot a load that is too light it may not allow the second sear to engage trigger and will not fire

This is only a problem for the second shot

Make sure your barrel select is fully engage as well

101 Under not firing
 

I know the original post is from 2016 but the same thing happened to my 101 which I bought this spring(2018). I've put ~10,000 rounds through it mostly shooting skeet. First a week ago, the Under started to not eject then today the Under stopped firing completely. I read this and maybe another blog or two. I then took off the stock (according to the manual not necessary for a normal cleaning). As I removed the stock, a strange small piece of plastic about 1/4" square fell out of the trigger area. I can't imagine how it could have gotten in there. It must have been in there all along. Anyway, put it back together and its again working like new. -go figure

Bashaw Sports
 

The fellas at Bashaw Sports did a little work on a 101 for me a few years back. Cost less and took less time than I was anticipating.