Repairs Prevent Riding

A few days ago when I rolled the recumbent Terratrike off the top of the Explorer I noticed the idler gear just behind the pilot seat had a missing tooth:

Sorry for the fuzzy photo, I got too close with the cellphone camera.  I emailed the factory to see what a new gear would cost me and they sell the whole spring-loaded arm for $49.95.  Not terrible, but it occurred to me this gear looked a whole lot like something I might already have on hand... 10-tooth idler gears on normal Derailleurs.  I have several "donor" bikes laying behind the shed and, sure enough, when I removed one and compared, it was an exact match.  Which is cool, since I just spent almost 50 bucks for new disc brake pads for this trike last week.  Seems like almost everything costs in the neighborhood of 50 bucks to repair failures on this rig.  Which of course is a screaming bargain compared to what almost any auto part costs nowadays.
I rode my 2-wheeler recumbent last week for the 12 mile trip each way to Edgewood and noticed it had a slight "Grumble" at speed on smooth pavement.
Today I thought I should take off the rear wheel, since that seemed to be where the grumble was coming from, and check and lubricate the bearings.  They weren't DRY, but hopefully a cleaning and greasy re-lube will help it roll silently for the immediate future.
After I reinstalled the newly re-lubricated wheel and checked the shifting to make sure I'd gotten the chain and gears mated properly, I noticed a slight "Chug-Chug" as the rear wheel spun.  I have slowly learned over the years to NEVER ignore strange sounds, no matter how slight.  As I slowly rotated the wheel watching for problems I spotted a nasty bulge in the tire:  It had a rip in the center of the tread  with the tube barely showing, just RIPE for a blowout.
Thank goodness I spotted this today instead of experiencing the unpleasantness of  a "POW!" while riding down the road somewhere.  I carry a spare tube but NOT a spare tire in my pannier.
After working on the bike/trike today I was covered with black grease and dirt, about as grimy as if I'd been working on one of the cars.  Bike grease and oil is NASTY.  All my pants I've ridden bikes with have at least faint blackish grease stains from unintentional contact with the chain.  Guess I should consider grease stains a badge of honor, Har.