I have a Heat N Glo SL-750TRLP propane fireplace. It was working fine at the end of the last winter when I turned off the pilot and gas supply for the summer. I just re-lit it for the first time this fall, and I noticed a few problems that weren't present last time I used it ~ 6 months ago:

1) ⅔ of the burner lights right away, but the remaining ⅓ requires approximately 15 minutes to light.

2) The flame color is blue even after the fireplace has been running for > 30 minutes. It previously started blue but turned yellow after ~15 minutes.

I'm planning to call a technician tomorrow, but just wondering what could have changed to cause this? Nobody has touched the fireplace between last season and this season.