Could a potentially failed powerhouse 135 cause the same symptoms as a tubular track center rail insulator failing?

The PH135 that has blown fuses or a tripped circuit breaker probably is not at fault and failing, but operating as expected (as in stopping the supply of power to an overloaded circuit).

It can be a tedious and arduous task to track down the root cause in your layout wiring and/or track, but is the only real answer.

Disconnect the PH135 from the layout, replace and reset and breakers, and test the output. It should read 18-19 VAC.

If you followed a conventional pattern with many blocks/power districts, use that to you advantage to quickly narrow down an arena(s) for the fault(s).

I had a 135 PowerHouse fail.

The screws are 'security' types that are deep and hard to reach to see what is inside. 

This is partially electronic, so it would be best to repair, but that is made to be extremely difficult. 

Without any power wires connected or powered rolling stock and engines, check for continuity between center and outside rails. Continuity will tell you it's a track problem.

If the PH135 works fine disconnected from the track then it's not the issue. 

Thanks guys.  It didn’t occur to me to try the 135 on a different loop...I’ll try that first before I proceed.  I’m afraid once I took it apart I’d be only able to take a complete layman’s glance for something obvious, and then shrug.  

If I remember correctly from the last time I did this, the O22 switches need to be continuity tested separately, along with the absence of locomotives & rolling stock with center rail pickups.  Can’t remember why, but perhaps it’s the fiber pins for the non derail function hampering continuity?

Tom